RTFM!

Hardly a day goes by where we don’t say to a reader or customer “Did you Actually open the installation manual?” One of those items we’ve seen one to many of are the Victron Battery Protect devices. These are great products but like anything Victron, their manuals are typically written for Victron trained technicians not the average DIY. They are also written in a generic world view and standards applicability will need to be assessed based on the installers location eg: ABYC/ ISO /RCD etc..If attempting to install Victron equipment as a DIY you have two choices;

1) Use a Victron trained dealer/installer (Preferred)

2) Research, research, research…

Research resources:

Victron Support Community

Boat  Electrical Systems (largest group of ABYC & ISO/RCD Electricians anywhere.)

Victron Battery Protect

The Victron Battery Protect is a low-voltage disconnect device intended to protect your batteries from over discharge. If purchasing one of these we strongly advise purchasing the “smart” battery protect. The model with smart in the name features Bluetooth for programming.It is definitely worth the extra few dollars..

What is so complicated? Honestly, I have no idea? The terminals on the Battery Protect are very clearly labeled IN & OUT?

The owners Manual is also extremely clear these are not bi-directional devices;

Despite the manual being very clear. Images like these keep popping up…

65A Victron Battery Protect: Completely Smoked!!

There are two scenarios here the 65A current rating has been exceeded. The unit was installed in a bi-directional manner where the owner was trying to use if for both charge and discharge….

The official word from Matthijs Vader the managing director of Victron..

Despite the manual and clear terminal markings stuff like this still happens

Are any of these failures the fault of Victron? The answer to that is a hard  no…All of these failures could have burned a boat to the waterline!

Here’s the reason these are not Bi-directional

As can be seen the Victron BP’s use FET’s as the switch not a relay like the Blue Sea LVD does…Is this bad? Absolutely not, it just means you need to RTFM….

Be Safe RTFM!

Marine Battery Banks & Over-Current Protection

A 300A (MRBF)Battery Terminal Mounted Fuse by Blue Sea Systems

In this article we will discuss fuse selection, fuse types, wire ampacity, Amperage Interrupt Capacity (AIC) and even potentially unsafe ABYC “exceptions to the rules”. In short, this article deals with why fusing your battery banks is a critical safety measure.

Bank Fusing Steps

1 – Know the amperage of the load you need to fuse

2 – Know the Ampacity of the wire you are trying to protect

3 – Determine the AIC of the bank you are trying to protect

The ABYC Standards – A bare Minimum not a Maximum

In regards to over-current protection of battery banks, owners should consider that the ABYC standards are a bare minimum requirement. In many cases, especially battery bank protection, certain aspects of ABYC E-11’s battery bank over-current protection should be considered as inadequate, potentially unsafe and below where a boat-owner should set their sights, if they want true safety. What the excerpt below is Saying is that any + conductor connected to a battery bank requires over current protection within 7 inches of the batteries positive terminal. This includes house banks, windlass banks, thruster & winch banks.

Your House Bank Requires over current protection!

Yes, I am an ABYC member, ABYC certified electrician and also part of the electrical sub-committee that helps develop these standards. Sometimes rational arguments made by the likes of Nigel Calder, myself and numerous others are over-shadowed in favor of taking a shortcut or to save boat-builders money. In many cases you can and should aim to exceed the ABYC standards. Specifically with regard battery bank fusing or sheathed/loomed or conduit protected wire.

Definitions Used:

Ampere Interrupting Capacity (AIC) – the maximum short-circuit current that an over-current protection device can safely interrupt under standard test conditions.

Source of Power – In regards to battery bank over-current protection the battery bank is the “source of power” that we are protecting the wires from.

Conduit – an enclosure that is part of a closed wiring system for insulated conductors and/or cables in electrical installations, allowing them to be drawn in and/or replaced. Conduit or sleeving also serves to protect from chafing and shorting.

Equipment Enclosure – the outside shell of equipment that provides personnel protection from electrical hazards, burns, rotating machinery, and sharp edges, and provides protection to the device from mechanical damage or weather.

Ignition Protection – the design and construction of a device such that under typical design operating condition, will not ignite a flammable hydrocarbon mixture surrounding the device when an ignition source causes an internal explosion, or it is incapable of releasing sufficient electrical or thermal energy to ignite a hydrocarbon mixture, or the source of ignition is hermetically sealed.

Loom – a flexible covering designed to protect conductors.

Main Over-current Protection Device – an over current protection device with no other over current protection between it and the source of power.

Pigtails – provided conductors integral to an electrical component or appliance for the purpose of connection to external circuits. eg; LED navigation lighting.

Self-limiting Device – a device whose maximum output is restricted to a specified value by its magnetic or electrical characteristics.

Sheath – a material used as a continuous protective covering, such as overlapping electrical tape, woven sleeving, molded rubber, molded plastic, loom, or flexible tubing, around one or more insulated conductors.

A battery bank fuse is there to protect the wire!

The ABYC Standards on Battery Bank Fusing:

Fuse Location:

The ABYC requirement is for a battery bank fuse is to be within 7 wire inches of the battery bank. The European ISO/RCD (which is law) requires the fuse be within 200mm. 200mm equates to about 7.9”. In this regard, the European ISO/RCD is essentially the same as the ABYC’s 7” requirement. The difference here is the ABYC standards are still voluntary. I only point this out because we hear time and again that the ABYC is not a law, and it is not, but the ISO/RCD (recreational Craft Directive) is a law.

These fuses, one for each bank, are in compliance with ABYC E-11. The one on the cranking battery exceeds and goes above and beyond the ABYC standards.

In the real world of boats and battery compartments meeting the 7” rule is not always as easy as it sounds. If you can’t get within 7″ then the next best thing is to be as close as possible but the wire should always be in a protective conduit or flexible loom, once the jumper to the fuse exceeds 7″.

If you’re having trouble meeting the 7″ rule, the Blue Sea battery terminal fuses shown in this photo are an excellent option for up to 300A. If trying to fuse a bank that may ever need to be used to start a bigger engine, you may need a Class T or ANL fuse and the correct fuse holder..

These fuses are excellent but they do add nearly 2″, in height, to a battery post, if vertically mounted so measure your battery compartment height carefully.

Exceptions to the 7” Rule:

While the standards do have an allowable exception for over current protection regarding cranking conductors. Nowhere in the ABYC standards does it suggests not fusing cranking conductors. In other words, the ABYC is not saying “don’t fuse a creaking conductor” they’re simply allowing you an exception to the rule if your engine is too big to be fused.

It is quite often repeated as fact on the Internet, by folks who don’t understand what they’re talking about, that the ABYC says “don’t fuse engine cranking conductors”. The standards say no such thing.

Other Exceptions to the 7” Rule:

Under ABYC E-11 the fuse does not always need to be within 7”. Depending upon the location & where the wire connects to, meaning the battery or other source of power, such as a battery switch, and when “contained throughout its entire distances in a sheath, or enclosure such as a conduit, junction box, control box, or enclosed panel” the fuse can be either at a maximum distance of 40” or 72”.

72” Exception to the 7” Rule:

40” Exception to the 7” Rule:

“Exceptions” to Bank Fusing – Do They Always Make Sense?

Remember above where we mentioned that the ABYC standards are a bare minimum and you can often do better? Well, exception #1 “cranking conductors is one area where the ABYC is simply leaving far too much room for dangerous installations.

In today’s day and age you can, and ideally should, strive to achieve better than the extremely low bar set by ABYC E-11 on bank fusing. Compass Marine inc. has been fusing cranking conductors since the mid 90’s and these circuits have likely undergone hundreds of thousands of engine-starts. I can count on two fingers the number of nuisance trips we’ve had.

#1 An engine that hydro-locked due to a scoop strainer installed with the scoop facing forward. (darn good thing the fuse tripped)

#2 A boat that tangled in lobster gear and the reversing gear was stuck in gear. The owner tried to start it anyway. (Again, it’s a darn good thing the fuse tripped.)

Sure, using the “cranking conductor” exception is an easy mark for a boat builder, as it saves them money, but many of us who do this for a living find this exception to be patently unsafe without also mandating the cranking conductors be located in a protective conduit/sleeve. Nigel Calder is one such individual who also believes this exception is not one to use (see excerpts below).

The argument a few of the members of the ABYC committees make is that starting motors draw too much current and are difficult to fuse. Ok, if this is the argument, why don’t we take a look at devices such as DC powered bow thrusters. A bow thruster is not a cranking conductor so by the ABYC standards that connection to the thruster bank must be fused.

This series wound thruster motor is exactly like a typical marine engine starter motor. The only difference is that it actually draws a lot more current, and for a lot longer, than you’ll find on the vast majority of marine engines.

The difference between a starter motor and a thruster are however huge. A typical engine starting duration ranges from about * 0.75 seconds to 1.5 seconds on average(*data Midtronics EXP 1000HD) . Bow thruster motors are rated for as much as 3-5 minutes and many owners use them for 30 seconds or more at a blast. The bottom line is this; a bow thruster is treating a fuse in a much more abusive manner than a starter motor ever will! The ABYC requires the bank feeding this bow thruster to be fused but not starter motors? This is about as nonsensical and hypocritical as your everyday politician( either side of the aisle, your pick)!

This particular bow thruster draws well over 1000A for in-rush, and physically maxes out our Fluke 376 which can measure to 1000A DC for in-rush. Under actual thrusting loads it typically pulls 330-365A, for as long as 30 seconds or more at a time. On land, with no load/water to move, it draws about 285A +/- which is pretty much spot-on for the motors 376A rating. Also keep in mind this is not the biggest 12V thruster we deal with.

“But, the motor says 3kW what about Ohm’s law?”

3 kW = 3000W If we take a typical no-load rating of the motor this is; 3000W/11.5V = 261A

11.5V is a perfectly acceptable voltage sag on a bow thruster bank under that type of load. However, as I mentioned, this is a “no-load” rating meaning no gears to turn, propeller to spin or water to move. This is how and why a 3kW motor can typically draw much more current than the face value 3kW rating.

“But, the rating plate says 376A, why does it disagree with the 3 kW rating?”

Yes, the rating plate may say 3kW and 376A but the motor wattage rating is a no-load rating. Put a load on any DC motor and it will draw more power than the no-load wattage rating indicates. See chart below.

One more example:

This is the current spec from an Anderson Electric Winch we installed. The ABYC requires these winch batteries to be fused. Notice how high the in-rush is (green square)?

And here is a chart showing the winch current draw based on winch load. As stated, apply a load to an electric motor and it will draw more than its face value rating.

The point in all this discussion on bow thrusters and electric winches is to examine why mandating over-current protection for DC bow thrusters/winches and then making “exceptions” for engine starting motors is actually pretty silly..

What would make a cranking conductor fuse exception ok?

A fuse exception would be OK if the ABYC actually mandated un-fused cranking conductors to be protected in a protective sheath, conduit, sleeve etc. like the 40” and 72” rules do, but the standards do not call for this. Unsleeved/unprotected wire is perfectly fine for a cranking conductor under ABYC E-11. Crazy? You Bet bet is!

What AWG do manufacturers suggest for cranking conductors?

Here are some minimum manufacturer suggestions for battery/starter cable from Westerbeke and Universal.

Universal / Westerbeke minimum wire size requirements (wire length round-trip)

2 AWG = 8′
1 AWG= 10′
1/0 AWG = 14′
2/0 AWG = 18′
3/0 AWG = 22′
4/0 AWG = 28′

Nigel Calder addresses the fusing of cranking conductors in his books;

Begin Quote – Nigel Calder:

End Quote:

and

Quote Nigel Calder:

End Quote:

A real-world example of why this exception can be dangerous.

Exceptions to the Rule vs. Common Sense

In August of 2010 a local yacht clubs junior sailing program had a chase boat returning to the dock with a few 8-10-year-old junior sailors, and their coach. They were aboard a well maintained 15’ Boston Whaler. As they tied up to the dock, the battery cables under the helm seat started to smoke. Within seconds the entire boat was engulfed in flames. The boat was a total loss. The kids barely made it off the boat before the fire fully engulfed the vessel.

Points to Consider:

• The ABYC standards do not even require a battery switch let alone a main bank fuse for this boat!
• This tiny Honda outboard is very, very easy to fuse with an MRBF battery terminal mounted fuse!
• This boat fire was driven by a single group 27 battery, into shorted 6 GA wire!

What if this happened when the kids & coach were out on the bay, not as they approached the dock? Safe? Hell no!

If a single G-27 battery can do this to the Honda outboards factory supplied wire, & this boat, what do you suppose two 8D cranking batteries will do to your wire & boat if the wire shorts?

A small MRBF fuse holder & fuse, that costs $30.00, would have 100% prevented this fire.

The bank below is capable of 18,000A of short circuit current!

The installer put the wires in protective loom and went above and beyond what the ABYC requires. Smart guy!

Fuses Work!

Below is an example where the owner’s boat was protected by a fuse. This owner had a 1/2/B switch and decided it would be a good idea to fuse both banks. A year after doing this DIY upgrade he had a plastic wire-tie fail and the large gauge battery cable came in contact with the engine.

The 300A fuse, that was protecting this wire, saved this owners boat from burning to the waterline.

Foolish to not protect all batteries with over-current protection or a protective conduit? You bet it is!

Bare Minimum Fuse Sizes

Let’s cut-to-the-chase on this. Below are the minimum bank fusing we prefer to see for any bank that could ever be called upon to start a motor. If your vessel has a 1/2/B switch both banks need to be capable of starting the engine.

Bare minimum fuse size for small diesel engines 8HP to 25HP = 250A

Bare minimum fuse size for medium diesel engines 25HP to 60HP = 300A

Above 60HP 75% of measured *inrush current as minimum fuse size.

*You will need a clamp meter such as a Fluke 376, or equivalent, to measure the inrush.

If you follow the above guidelines, you will not suffer “nuisance trips” if fusing your starting bank.

If your engine is too large for a fuse put the entire length of the cranking conductor in a protective conduit or protective loom! Unprotected battery cables are a fire waiting to happen!

Selecting the Proper Type of Fuse:

Battery banks larger than 255Ah should be protected with fuses not breakers. The following types of fuses are suitable for main bank protection:

ANL

CLASS T (preferred for Li-ion& large AGM Banks)

MRBF

These fuses are available from Blue Sea Systems and other reputable sellers. They should however be “Ignition Protected” fuses if installed on a gasoline boat and Blue Sea Systems is the only one I know of offering ANL fuses with ignition or spark protection for ANL’s. Class T fuses are not technically IP rated however they are fully encased in a metal body. Class T fuses have simply not been tested for IP rather than do not meet IP. In speaking with Blue Sea systems I was told they have no documented cases of an IP breach on any Class T fuses.

Remember, the main battery over current protection (OCP) or over current protection device (OCPD) is sized to protect the wire. The main bank fuse is not there to protect the down-stream equipment. Those fuses would be located after the main bank protection fuse. This is often misunderstood.

You can always go smaller with OCP than the wires ampacity rating, but ideally should not exceed the ampacity rating unless you are fusing the battery bank and the bank could potentially be called upon to crank a motor. The main bank fuses are there to prevent the wire from overheating, melting and starting a fire in a dead short situation. Generally speaking a fuse is sized to not exceed the maximum ampacity of the wire. In certain instances the ABYC allows for up to 150% of the chart below.

What if my engine draws more than the wiring is rated for?”

Nigel Calder clearly addressed this above and this is actually not uncommon at all. Many builders undersized starting wire for many years, and got away with it, due to the short-duration starting circuits are physically current-loaded for. Today, most builders have come up closer to where they should be for wire ampacity.

A good example of this is the original Universal M-25 as shipped on Catalina Yachts in the 80’s and most of the 90’s. Catalina used to ship the Universal M-25’s with 4GA battery wire. In the late 90’s they began shipping the same engine, a Universal M-25XPB, with 2/0 gauge wire. Going from 4 AWG to 2/0 AWG is a huge improvement. If you have small gauge wire, an upgrade to larger wire can be a very good investment. Your engine will also start quicker and the starter will see a lot less voltage-drop. Larger wire means you’ll be able to develop more cranking current for faster starts. Nearly every sailboat I went aboard during the last boat show, including a tailerable 28 footer, was using 1/0 or larger wire with 1/0 and 2/0 being the most popular in boats over 30′.

Won’t the starters in-rush current blow my fuse?

First, let’s identify what in-rush current really is? In-rush current is the very brief spike in current that the starter undergoes to get the motor to begin turning over from a stopped state. The in-rush duration is usually about 100ms to 300ms long, and is not long enough to blow a properly sized fuse. ANL, MRBF or Class T fuses are not sized for the inrush, they are sized so they don’t nuisance trip when cranking an engine.

Compare the in-rush duration to a fuse rated for main bank protection and it becomes clear as to hoe this is so.

ANL FUSE- TRIP DELAY CURVE

CLASS-T FUSE -TRIP DELAY CURVE

MRBF TRIP-DELAY CURVE

Contrary to popular misconception fuses don’t always trip at their face value rating. You also need a long enough duration at high current. As can be seen above, each fuse has a trip-delay curve. These curves are from Blue Sea Systems.

If you look closely, a 300A Blue Sea Systems ANL fuse can support 600% of its rating, or nearly 1800A, for approximately 0.5 Seconds. The inrush duration is not this long.

If we look at the trip-delay curves above it becomes quite clear that ANL, Class-T or MRBF do not trip at face value unless the duration of high-current is long enough.

For example, a 300A Blue Sea Systems ANL fuse can handle 300% of its rating for an entire second or 900A. Peak cranking currents just don’t last this long. If we look to the far right of the trip-delay graph you can see that it would take nearly 500 seconds or 8.3 minutes at 150% of the ANL fuses rating to actually trip. For a 300A fuse this is 450A for as long eight minutes or so. This is the reason why fusing cranking circuits is not the problematic concern some make it out to be. You just need to size the fuse correctly.

300 AMP ANL Seconds vs. Trip-Amperage

.7 Seconds =1800A
1 Second = 900A
5 Seconds = 500A
500 Seconds =450A

AIC & Why It’s Critically Important!

AIC stand for Amperage Interrupt Capacity. The AIC is sometimes called “interrupt capacity”too. AIC is the short circuit amperage capacity the fuse or breaker can “interrupt safely” without welding shut, blowing up and losing “ignition protection” or jumping the gap and failing to provide protection..

The ABYC Standard

The green arrow is pointing to a specification that can only be met by a Class T fuse!

Table 3B below.

Not All Fuses/breakers are Created equal!

Not all fuses/breakers are created equal. Always Stick with fuses by Blue Sea Systems, Cooper Bussmann or Littlelfuse.

When ordering from less than reputable sellers make sure the products can meet the following;

Avoid purchasing fuses/breakers off of Scamazon! The customer below learned a very hard lesson. The pictured breaker came from Amazon and the customer certainly got scammed! The 200A breaker was consistently tripping every time his alternator output got to 85A! Amazon refused to publish his review on the product! The alternator load dumps caused his alternator to fail and also took out his brand new B&G plotter!

And here’s a guy who’s budget breaker welded itself shut! This is why AIC Matters!

*Images below courtesy Attainable Adventure Cruising

The welded & melted breaker

Below is another example of why AIC maters. The fuse below was attached directly to the battery + terminal and when it tripped it failed in a manner that it kept allowing current to pass. The owner noticed a fumy smell and it was his bilge pump starting to melt.!

The meter is still showing continuity even though the fuse clearly tried to blow! The AIC rating of the fuse maters!

The above ATC Fuse only had an AIC of 1000A yet was directly connected to a bank of AGM batteries that could deliver 20,000A of short-circuit current

ATC Fuse AIC

What Fuses have an AIC that is suitable for a cruising boat bank?

Class T, ANL and MRBF fuses all have an AIC that can be suitable for house banks. If you have a large bank of AGM or Lithium batteries then a Class T fuse is the best fuse to meet the AIC requirements. For LiFePO4you really want to use class T. ABYC E-13 specifically calls this out.. The AIC rating of Class T fuses is 20,000 amps at 125V. It is significantly higher at 12V but Blue Sea Systems has not run the AIC tests at 12V. A 20,000A rating at 125V is a very, very impressive AIC rating. The Class-T fuse is the most robust fuse we use in the marine environment because it is fully metal encased.

ANL fuses have AIC of 6000A at 32V and MRBF fuses are 10,000A at 14V.

What about Breakers & AIC?

The concern with AIC & breakers is that breakers can literally weld shut before tripping, if the bank has enough short-circuit current behind it. For smallish house battery banks, you ideally want an AIC rated fuse or breaker of 5000A AIC or greater. Even Blue Seas Best class of breaker, the 187 series is only rated at 5000A AIC.

Just one group31 Odyssey TPPL AGM is capable of 5000A of short circuit current! Please understand that AIC is not just for large AGM banks or LiFePO4 batteries. A single 100Ah Group 31 Odyssey AGM battery can deliver 5000A of short circuit current into a dead short. A 200Ah bank of Group 31 Odyssey AGM batteries is 10,000A into a dead short. This is why the AIC rating of the over-current device is critically important.

The actual ABYC requirement for batteries is that any bank over 255Ah needs 5000A AIC rated protection or greater.

Cheap Fuses have no place on your boat

For the ABYC Li-Ion Battery sub-committee I spent A full day blowing all types of fuses and one thing that was seen very early on is that all fuses are not at all created equally. When a fuse trips it needs to trip in a safe manner. Knock of fuses, often found on the internet for car stereos, etc. are not built to the same standards as fuses from the likes of Blue Sea Systems, Littelfuse or Cooper Bussman. With a quick phone call any of these three companies you can quickly get all the testing data for any products they sell. Go ahead and try that with off-brandfuses/breakers you find on Amazon I know what the answer will be, we tried to do it for one of our customers who had a Scamazon breaker blow up one of his alternators. It tripped at just 110 A and was rated 250A! Sorry, no, this is not covered under warranty!

Blue Sea Systems ANL fuses have an IP rating “ignition protection” which is important on boats as the fuse must fail/trip safely so as not to ignite any on-board fumes. In the image below we have a bunch of cheap Amazon ANL fuses. A Blue Sea Systems ANL is built with G10 fiberglass sheet, features four rivets holding it together and uses a very durable Mica window. The cheap ANL fuses are a plastic body, two rivets and they use thin plastic windows that are prone to blow out when the fuse trips. We tripped 22 of these cheap fuses and the windows failed unsafely 20 out of 22 times. You can see the blown-out window in this image. When in doubt stick with fuses and fuse holders from Blue Sea Systems, Littelfuse or Cooper Bussman.

The photo below is a prime example of what can happen to a cheap ANL fuse. These claimed to be “ignition protected” (IP) and AIC rated fuses. After multiple emails to the vendor, they failed to provide any documentation to back any of these claims up? When buying fuses on Amazon it is certainly buyer beware! A few weeks later I noticed the specifications had magically changed and they no longer claimed IP or an AIC rating. Sadly, the only data I was able to find on the fuses was “Made in China“.

The fuses below were connected directly to a LiFePO4 lithium battery bank and then the circuit was shorted. The fuse trip was so violent, it literally blew the windows out of the fuses. This is an UNSAFE failure mode for a fuse. It failed for both AIC and ignition protection safety.

What About Victron Lynx Distribution Buses?

Victron has a beautiful line of distribution busses called the Lynx series. The Problem with these busses is they employ MEGA fuses that only have a AIC of 2000A. The solution is quite simple. You simply feed the distribution bus with a fuse that has the correct AIC Rating for the battery bank.Once the mega fuses  are behind the main distribution fuse, a fuse that has the correct AIC rating, the MEGA fuses are now fine.

The Solution:

Pro Tips:

If you lack battery compartment height, and your batteries have lead posts, a military post can get you horizontal with an MRBF.

MRBF fuses work really well mounted to busbars

ANL or class T fuses/holders can be bussed together using copper bar stock from McMaster-Carr

Fuse Safely!!

If you’ve read my articles for any period of time you probably realize that there are a few things that I can’t stand;

#1 well marketed products that actually suck in reality.

#2 Pop-up brands ( pop-up brands =companies that never existed before Amazon) that slap their sticker on the cheapest Chinese products they can find and then market them as a reputable brand.

Things I Like;

#1-manufacturers who aren’t afraid to step out on a limb and go so far above and beyond what the rest of the industry is doing that it makes the competition look like they’re stuck in the 1940s. Victron does that with these chargers.

Sadly, the portable or maintenance/”trickle” charger market is flooded with products that are stuck in the 1940’s. Most of them I wouldn’t charge a $25.00 U1 garden tractor battery with.

My dad’s whole adult life was spent as an antique car collector. Most of these cars sat for months and months and months without any use. So, over the years my dad collected a massive pile of trickle chargers or maintenance chargers as some of these companies like to call them . Every single one of them, that we recovered from his barn after he passed away, is the biggest piece of crap I’ve ever seen. I now understand why my dad replaced batteries so often. The chargers he was buying were pure junk.. His collection included brands such as the well-known “Battery tender”, Schumacher, Duracell, NOCO, Diehard, Harbor freight, Guest, Century, and even one that was stickered by John Deere.

A number of years ago one of our wholesalers took on the NOCO line. It was marketed as the second coming of Jesus. I bought a bunch of them to maintain customers batteries over the winter only to find out they do no such thing. They turned off after the battery has been charged and then they go to sleep/turn off. They do not do a float stage. When the charger turns off the battery then self discharges and can start to sulfate.

All in all I bought three or four of these NOCO “chargers”. I know, I know, I failed to do enough research before pulling the trigger! I just bought them based on the introductory price and you guessed it the glossy marketing. Stupid me!! After realizing how bad these chargers were I, took about three or four of them up to our camp where they wound up charging the Kubota tractor the plow truck, a couple of old vehicles we have up there, ATV’s, snowmobile’s etc. Over the winter we threw one of the NOCO’s, a G3500 on the plow truck. It’s a Ford F550 diesel. When it finally snowed and we went out to start the truck all it did was make a “click, click” …The battery charger was still on and the light was solid green indicating it was ready to go and the battery state was at 100% No such thing, the batteries were at 11.6 V before we even tried to start it. The charger was still saying they were perfect and sitting at 100% SoC. Click click click….. We wound up having to replace the batteries on the plow truck thanks to that well marketed NOCO charger. Since our debacle with the NOCO chargers, Victron launched its new series of IP 65 and IP 67 chargers. The NOCO’s up at camp, and here in my shop, have all been replaced by Victron chargers.

Let me sum this article up in one line for you:

There is no need to invest in any maintenance or portable charger other than the VICTRON Blue Smart IP 65 OR IP 67’s!

The entire point of this article is to get you to stop buying crappy chargers, as I did, that are marketed as the second coming of Jesus when they are far from it. For this article I spent hundreds of hours testing the 5 gal bucket full of portable charges my dad had, including the NOCO chargers that we had. None of these chargers were worth the cost of the orange 5 gallon Home Depot bucket I had them in, yet some of these chargers cost as much as $150 or more. Some of these chargers were so bad they only charged the battery to 13 V and then stopped at that point. You cannot charge a battery without hitting an absorption voltage and do so in a healthy manner. Some of the chargers, such as the NOCO would charge to an absorption voltage then shut off completely with no float whatsoever. One of the NOCO’s would not turn back on until the battery bank got down to about 12.52 V. The other one I had allowed the battery bank to fall all the way to 11.6 V and it never turned back on. This is the charger that killed the batteries on the F550.. NOCO swears this cannot happen yet it did and my Fluke meters are NIST calibrated..

The key to understanding some of these “well marketed” chargers is this:

As can be seen below, from a support chat with NOCO, their chargers do not float charge the batteries. This one charges to 14.5V then turns off and waits for the battery voltage to drop to 12.7V. It then repeats the 14.5V>drop to 12.7V repeat>repeat.. Apparently, I got two defective chargers that need to be sent back? What are the odds of that?

Definitions:

Trickle Charger – a trickle charger is a charger that puts out a constant-current and has no voltage regulation. A true trickle-charger should never be used on lead acid batteries and be left unattended. Lifeline battery goes so far as to prohibit the use of trickle chargers.

Maintenance Charger-a charger that is supposed to bring the batteries to an absorption voltage and then drop to a float voltage. Throughout this testing we discovered that this definition is not adhered to by most of the manufacturers marketing and selling “maintenance chargers”.

Smart Charger- a charger that does multiple stages of charging; Bulk, absorption and ends with a float voltage.

The Victron Blue Smart IP65 & IP67 Chargers

The Victron Blue Smart and IP 65 and IP 67 chargers are by far the best small amperage chargers you will find at any price, yet they are very reasonably priced. These chargers cost less than some of the other so-called “maintenance” chargers out there, yet they do far more and feature full custom programmability.. They’re also covered by a five year warranty!

The BlueSmart IP65 chargers (water resistant) are available in 12V- 5A, 7A, 10A & 15A + 24V 5A & 8A.They are available in both 120V (North America) and 230V models.

B

One of our IP65 12V 5Achargers set up to maintain a Firefly Carbon Foam Battery.

like many Victron products the IP 65 and IP 67 chargers are Bluetooth compatible. These chargers can be custom programmed to charge any type of battery you wish to charge including LiFePO4. All you need to do is download the Victron connect app.

When you open the app your charger should show up in the device list. If you have multiple chargers, as we do, you can name each charger. As can be seen from this list my phone is seeing three of our Victron IP65 chargers. One of the chargers is set up to charge firefly batteries. One of the chargers is set up to charge Lithionics and one of them is just named charger #2

Another cool feature of the IP 65 and IP67 chargers is that you can run them in power supply mode or in battery charger mode. It can run as either a multistage battery charger, or a power supply, it’s your choice.

This is the main page of the app. To change anything you simply click the gear icon as pointed to by the green arrow.

Once you click the gear icon you will land here. In the section with the red box you can choose any one of Victron’s pre-defined programs or a custom saved program of your choosing. You can also select full amperage , in this case 5A, or a slow 2A charge for smaller batteries.

For Custom Programming you toggle at the green arrow;

Once you click “Advanced Settings” You will get a Lawyer warning;

On the next page you select “User Defined” then click on “Expert Mode”.

Next we’ll set the absorption voltage by clicking on the absorption voltage line;

Next you set your absorption voltage by using the + & – arrows and selecting OK. Yes, you are seeing that correctly. Victron allows you to adjust voltages to the hundredths position! If you want to set it at 14.67V instead of 14.6V, go right ahead. This feature alone is enough to keep all the other chargers back in the 1940s..

Repeat the same steps for setting the float voltage. Please note that Victron actually treats you like an adult and allows you to either enable or disable the entire float stage. Your Choice! For the Firefly AGM I have set float to 13.4V.

These are the other parameters that can be set;

What the Heck is “Storage voltage”?

In one of my articles from 2010 LiFePo4 batteries on Boats, I go into great detail about how LiFePo4 batteries cannot be charged like lead acid batteries. Float charging LiFePo4 batteries is not necessarily good for them. They prefer to be stored long term at about 50% state of charge and not be left on permanent float. I discussed how we we need to have different terms, float voltage and storage voltage. Well, wouldn’t you know Victron is the first to do so & it’s brilliant. Even though this is a Firefly battery, the inventor of these batteries Kurtis (a Fellow Mainer) preferred to see them at 13.2 V maximum for float voltage. So, I was able to set a short float of 13.4V which is what the North American importer says is okay. Then after 13.4V, it drops down to a 13.2V storage voltage. There is no other charger manufacturer that allows you to set a storage voltage!

So, How Does The Custom Programming work?

For this testing I chose to use our fluke to 289 set for voltage data logging. I didn’t realize it at first but it was set to capture once each second. This makes for a huge .CSV file. Nothing Excel couldn’t handle, of course. Note the accuracy of the absorption voltage which had been set to 14.4V!

This is what our custom programming looked like;

As can be seen the Victron BlueSmart IP65 performed exactly as it was programmed. With the new Victron IP 65 and IP 67 chargers there is absolutely no reason on earth to purchase anything else. You get what you paid for…

Accessories

Victron even offers some cool accessories that are also reasonably priced.

While the ring terminal plug and quick-clips come with each charger they are also available separately.

FAQ

Q: Can I permanently mount these chargers?

A: Yes, these chargers can be permanently mounted and they have four mounting holes specifically for this purpose. Any permanent mounting must be done to Marine safety standards including a fuse in the battery positively than 7 inches of the battery and all other protocols followed. the IP 65 charger needs to be mounted in a dry area just as you would with any dry mount charger. When permanently mounting these chargers will need to use the ring terminals not the alligator clips.

Q: Do these chargers meet the safety standards?

A: Both theBlueSmart IP65 and the IP67 chargers are UL 1236!

Q: I have a Victron Orion TR Smart and it runs hot How hot do these chargers run?

A: Both the IP 65 the IP 67 are incredibly efficient chargers. To test this out I discharged a 125 amp hour Lithionics LifePo4 battery to 0% SOC and set one of our IP65 chargers to 5A and let it go. After 20+ hours of continuous bulk charging the charger was barely warm to the touch. There are many chargers in this size range would have burned themselves up trying to tackle this.

Victron IP65 & IP 67 Wish List/Shortcomings:

#1: when these chargers are set to run at their full amperage, there is slight voltage drop between the charger and the batteries. They really need to make these chargers compatible with the Smart Battery Sense which would provide battery temperature and battery voltage data over Bluetooth.

#2 There are many lithium iron phosphate batteries out there that require an absorption duration that is shorter than one hour, the current minimum. This is a simple programming change that many of us in the industry have been asking for for Since these charges were launched. I don’t know why Victron has not been able to do this?

#3 No US 120V 6V charger in this line-up.

Pricing:

I should not need to mention this but I will. Always buy your Victron components from a reputable dealer, preferably one who also installs Victron components or who can provide you tech support. Big online monster retailers do not provide any support. You can usually tell the dealer is an upstanding legitimate veteran dealer because they abide by Victron’s MRP. If you find pricing on any of these chargers that is below what you see here ,walk away from the dealer! They are either a gray market dealer or adealer who is not abiding by Victron’s strict policies. If they are willing to circumvent their dealer agreement they’re willing to screw you too.

Blue Smart IP65
12V5A=$89.25
12V7A=$116.45
12V10A=$138.55
12V15A=$159.80
Case for IP65 $28.05

Blue Smart IP67

12V7A =$111.35
12V13A =$131.75
12V17A =$144.50
12V25A =$211.65

Lead is Dead (almost)

You may be wondering why I am saying lead is dead ?The answer to that is simple; lead acid battery makers dug their own graves by grossly misleading the general public. They know damn well none of these batteries will never meet the cycle-life claims out in the real world whwere PSoC use is a reality. Why? Because the real-world is not a white coat white glove laboratory and in the real world “sulfation-happens”.

Claims of 1000 cycles or 1200 cycles or 1600 cycles is as laughable as Jim Gaffigan beating Usain Bolt in the 100 meter dash. In a battery use survey conducted on sailboatowners.com, the largest ever of its kind with 1480 users surveyed, the vast majority of boat owners reported they rarely if ever get more than 150 cycles out of their lead acid batteries. 150 cycles!!!!! Many of these are batteries that have claims of 100 to 1200 cycles or more. Laughable is about the best way to describe it. Lead is dead because the manufacturers dug their own graves by misleading their customers. Perhaps if they had been more honest in setting reasonable cycle-life expectations the mass exodus from lead to LiFePo4 would not be quite as rampant?

The image below is but one example of why I can say lead acid battery cycle-life claims are laughable. I don’t and will never make a claim like this without data. We have been conducting capacity test on lead acid batteries for close to 20 years. While the equipment for capacity testing batteries has gotten significantly better, the quality of the lead acid batteries has not. This poor customer purchased a brand-new bank of Trojan SCS-225’s in the spring. His boat is on a mooring and he did not have solar. I explained to him the batteries may only last 1 to 2 seasons. He was very surprised that based on Trojan’s claim of 600 cycles to 50% depth or discharge. The results below are not atypical. The battery is at 63.4% state of health in just one season. By industry standards a lead acid battery is considered end-of-life when it can only deliver 80% of rated capacity. 20+/- years of testing marine use batteries to BCI Testing standards has taught us that claims of 1000+ cycles from lead acid are about as fairy tale as Tinker Bell..

These days LifePo4 has come down in-price enough to be at near parity with AGM & Gel in a $$ to usable Ah Comparison. When we add in $$$$ to Ah & include cycle-life, LFP is wiping the tears of the lead acid battery makers off the floor..All that said.. Let’s take a loot at current prices;

Lifeline GPL-31XT– AGM- 125Ah X 3 for a 375 AHBank=$1596.96- 187.5 USABLE Ah @50%DoD(at best *300 hundred cycles(real world usage)) =**8.52/Ah
*20+ years of read world experience including many hundreds of capacity tests..

KILOVAULT HLX+ 2400X  2 400Ah BANK= $3090.00 for 320 USABLE Ah @ 80%DOD-5000+/- cycles=$9.65./Ah

KILOVAULT HLX+ 2400  X 2 for a 400AH BANK= $3090.00 for 400 USABLE Ah @ 100%DOD 2000 cycles=$7.73/Ah

A t 100% DoD the cost per Ah is only a little more than AGM

What About Cost per cycle?

HLX2400 Cost per cycle@ 80%DoD=0.62

HLX2400Cost per cycle@ 100% DoD=$1.55

LiFeLineAGM Cost per cycle@ 50% DoD=$5.32.

Drop-In Pluses& MinusesPreface:

This article discusses 12V (nominal) LiFePo4 Drop-in batteries for use on boats.

This is the first article I’ve written since I suffered a major stroke on September 1 (nearly died). It took me six+ months of recovery to get to this point. I am writing this with new speech to text software(Dragon) which is not easy to master and I only have one finger to type with(my left arm/hand are still paralyzed.. My vision was also affected by the stroke so working at the computer for more than about 30-40 minutes a day is exhausting(though with hard work my endurance is slowly getting better). My brain is pretty worn out after 30-40 minutes, so an article like this has taken me more than120 hours to author. I’m getting it done but everything is just taking a lot longer. I am committed to MarineHowTo.com and this article is just the beginning of my recovery. I had started the outline of this article back in August before I had the stroke..

 

What do we recommend for drop in Batteries?

For the highest quality; Lithionics

We also love the KiloVault HLX+ batteries

Good Product assembled in the USA; Battleborn

A Tremendous value are the batteries by *SunfunKits.com

(*use coupon code; marineht for an additional 5% off at sunfunkits.com)

Discuss what you read about in this article in the groups below:

LiFePo4 Drop-In Batteries For Boats

For general Marine electrical systems discussions; Boat Electrical Systems

I Actually Use LiFePo4

It’s important to know that I’ve been using lithium iron phosphate batteries on my own vessel since early 2010 I built my battery bank back in 2009 well before any of these drop-in batteries even existed. My LFP bank will be 13 years old on May 10 of 2022. The bank has in excess of 2200 cycles on it & most every single cycle has been to at least 80% depth of discharge with many many, many cycles (at least 100+ cycles) going to 0%. That battery bank can still deliver 100% of its 400Ah rated capacity so LFP batteries can last, where lead acid don’t.

Having been using LFP since 2010, you could not pay me to go back to lead acid..

Important:This article is not intended to pick on any manufacturer at all. It is intended only to make you a more educated buyer. Where it was possible brand names have been obscured..(I do call out one manufacturer but that is rare for me).

Drop-In LiFePO4 Batteries, don’t you just drop them in?

No you don’t! Any consideration of LFP batteries on a cruising boat must be treated as a system wide approach.Don’t just take my word for it. Boat US is one of the largest insurers in the US.

But, But, they say “drop-in replacement for lead acid?”

“Do Not Connect to analternator”?WOW!I’ve never seen a lead acid battery disallow connection to a non-smart alternator??Drop-in? Apparently not so much?

Terminology Used:

• LiFePO4= Lithium Iron Phosphate also called, LiFe & LFP
• BMS= Battery Management System
• C-Rate- “C “= Capacity and the rate is usually depicted as 1C, .5C.,.33C, .02C etc. A 100Ah battery with a charge rate of .5C would be 50A charge current or 100Ah ÷.5 = 50A
• Load Dump- A BMS Disconnect during charging which disconnects the battery.
  
• VPC- Volts per cell
• Pack voltage- voltage of the entire battery measured at the packs positive & negative terminals

What is a “drop-in battery?

A drop-in lithium iron phosphate battery is a self contained battery that comes in a standard lead acid case size e.g; group 24,27,31 group 4D, group  8D etc..These batteries are self contained and should always have a BMS built in.. Batteries that use an external BMS such as Vicron or some of the Mastervolt or Lithionics batteries are not considered drop-in batteries.

Ignore The Trolls & Safety

Internet trolls pollute the Internet like cigarette butts pollute city sidewalks and gutters. You know who I’m talking about, the undereducated know-it-all who enters any conversation regarding lithium iron phosphate batteries in a Facebook group or boating forum and   starts with; “The only people looking at lithium iron phosphate batteries are the ones who want their boat to blow up”. A great example of this can be found in the “parting shot” of the April /May 2022 issue of Professional Boat Builder Magazine.. Even though the parting shot is editorial in nature,Pro-Boat should be embarrassed by that piece and the complete lack of research on the authors part. Pro-Boat normally works with authors who are actually experts in their field such as Steve D’antonio or Nigel Calder but the author failed to do any research on this topic and put out a grossly under researched apiece..

Let’ cut out the BS right now. LiFePo4 and LiCoO2 (Boeing) are about as different as water and gasoline in terms of resistance to burning/exploding. While LiCoO2 and LifePo4 are both Li-Ion batteries, the chemistries are vastly different in terms of safety. Let’s not forget Flat-Earthers still exist too…

When you see these trolls politely ignore them &, as the internet goes, “don’t feed the trolls“..

Li-Ion= Rechargeable Li
Lithium = non-Rechargeable Li

Don’t just take my word for it here is the FAA

A Reader Challenge

Reader Challenge:I will continue to offer a challenge that I have been offering now for 10+ years on the Internet and that is; the first person to bring me an image of a lithium iron phosphate cell, properly installed, that erupted into flames or resulted in an explosion due to overcharging, I will pay them$50 cash for that image! In 10+ years not one person has been able to bring me such an image…This is because LiFePo4 is an extremely safe chemistry.

A Dramatic example of LiFepo4 Safety

The image below is but one example of the safety of lithium iron phosphate batteries. The cells below came out of a drop in battery where the solar controller failed & the 100V+/- array started feeding hundred+/- volts to the batteries. The BMS tried to protect the batteries but once the BMS shut off. in the solar array was still feeding 100V+/- to the chip in the BMS. Once the chip failed the 100V made it to the FET’s and they too failed allowing the full array voltage to get to the LFP Cells.

No fire, no explosion just swollen ruined cells & cell venting.

The Cells were overcharged so violently that it blew apart the metal case!

HOW IS A DROP IN BATTERY MADE?

A 12 V (nominal) lithium iron phosphate battery is made from four 3.2 V cells wired in series. This is referred to as “4S”. This makes the battery a 12.8 V rated battery. The difference between lead acid and lithium iron phosphate is that each cell in a lead acid battery is a nominal 2 V cell but in a lithium iron phosphate battery each cell is 3.2 V. So, a 12 V lead acid battery requires six 2V cells and an LFP battery only requires four  3.2 V cells.

START WITH THE CELLS & BMS

There are currently three different cell form factors being used in drop-in batteries. the first is called prismatic these are square blocks that nest together and most often require what is called cell compression,the Chinese call this a “fixture” . The “fixture” is used to prevent cell swelling / bulging during charging .

The second type of cell that is commonly used in drop-in batteries is called a cylindrical cell this can be anywhere from the size of a AA battery up to approximately the size of a D battery. Cylindrical cells are quite robust because they don’t need cell compression as the cylindrical form factor prevents swelling. The drawback to cylindrical cell batteries is that they typically require lots of spot welds to connect the cells in parallel cell blocks before they be are put into series series.

the third type of cell for drop-in batteries is called a pouch-cell we typically do not advise pouch cells for use on boats where vibration can be high. pouch cells can be easily ripped and often times they are just dropped into an and aluminum housing that can sometimes have sharp edges. pouch cell drop-ins are getting better and these days have less chance of ripping but prismatic or cylindrical is typically better for use in high vibration environments.

PRISMATIC CELLS & BMS

CYLINDRICAL CELLS & BMS

Pouch Cells

ADD A  BATTERY CASE

Clearly I’ve left out a lot of the important details of the manufacturing of a drop-in battery. In order to build a battery properly the cells must be impeccably matched before the the cell block is assembled. By impeccably matched I am talking about cell to cell Ah capacity and cell to cell internal resistance. If the cells are not carefully matched the BMS inside the battery may never be able to keep up with balancing.We have seen this in numerous instances with drop-in batteries.

What is a BMS?

BMS stands for battery management system. A battery management system is used to protect the individual cells inside the battery. Each 12.8 V (nominal 12 V) drop-in battery must use a battery management system. You could also call a BMS a cell protection system as it actually serves to protect the battery cells inside the drop-in battery. The BMS will protect the battery cells from such things as temperature voltage and current. The BMS also serves to balance the cells should they get out of balance. The BMS protects the battery by disconnecting the battery from the charge sources in the loads. Lead acid batteries do not do this.

Insane Market Growth  of Drop-In Batteries

In the last two years the proliferation of lithium ion phosphate(LFP) drop-in batteries has literally gone berserk. Drop-in technology has finally advanced far enough that I believe it’s now worth discussing in an article. I had previously avoided this topic because many of thethe early drop-in products were pretty poorly engineered, BMS’s had weak power handling etc..

Disclaimer: MarineHowto.com does not currently sell any lithium iron phosphate batteries. Health issues (a near deadly hemorrhagic stroke forced what is perhaps the permanent closure of my local electrical & on-line businesses.We are also not involved in any affiliate programs that could potentially sway our opinions! This site, like always, is for your education only. We want to ensure that you do not get ripped off in the field LFP drop-in batteries. What you get here is an expert opinion that is based on many years of experience in this field(since 2007). With no money potentially swaying these opinions, you’ get an unvarnished view.

While the internet is full of folks claiming to know what they are talking about sometimes it is easiest to just use a photo. The image below shows the ABYC marine safety standards that I work on. I have been involved with the lithium-ion subcommittee since it was first formed back in late 2013. I was personally invited onto this committee by the committee chair.

Beyond being a Marine electrician/engineer, I have been using lithium iron phosphate batteries on my own vessel since Spring 2010. And yes, that  bank (built well before drop-in LFP batteries even existed) is still going strong and it still delivers 100% of its original capacity when capacity tested.

I am also a voracious reader & research junkie;

As can be seen from the image below I have a massive collection of technical documents,research papers&white papers. Everything below is in regards to lithium ion phosphate batteries. I run a 32 inch monitor and I can’t even come close to fitting everything onto one page for a screen grab. This LiFePO4 folder alone has 377 PDF documents on lithium iron phosphate batteries. Yes, I have read them all…

LFP drop-in batteries have come a very, very long way in the last few years but this does not mean there are no sleazy manufacturers left out there. How do you avoid 98% of the poor LFP products? Easy, don’t buy directly from China on your own. If you don’t know what I mean by this I would urge you to spend some time on Will Prowse’s YouTube channel but, please don’t focus on his reviews(in a marine application sense), instead focus on how many failures he’s had cutting open & examining drop-in lithium iron phosphate batteries! Please remember that a manufacturer who is sending Will Prowse a battery often knows darn well who he is.. They still fail to send him well-built / well executed batteries many of them lacking cold-weather protection (You can’t charge LFP below freezing) even though they frequently lie and tell him the battery has it.. If guys like Will Prowse can’t pick quality batteries out of China how can you expect the average Joe to wade through all the murky information and get good LFP drop-in batteries directly from China? Hey, I’m not complaining, Will has indirectly sent us a lot of paying customers! These customers have had a number of issues with batteries,cells or BMS’ he’d reviewed. We’ve made a lot of money testing these batteries in our lab, only to tell the customer they had  been sent “B-grade or reject cells etc… This sort of stuff, has been sold as  “A”grade” but, the customer got “B” grade or reject products. This scammery runs rampant on Aliexpress, Alibababa, eBay, Bangood Amazon etc. etc. so be very careful when ordering direct from China because you’re on your own once you do..!

Purchasing- Rule#1

Rule number one for purchasing  lithium iron phosphate drop-in batteries is that you always want to buy from a well established US or North American company!(This site is read world wide but is still a US based company. (Insert Germany UK, Norway, Sweeden etc. for USA), even if that company is having the batteries manufactured in China. Hint: All lithium iron phosphate cells are manufactured in China. Some US manufacturers such as Battleborn choose to import the components from China and assemble them here in the US. This allows them to better control assembly quality. You want, and need a presence here on North American soil (insert your country here)  to ensure that the company can stand behind the product and you are protected by US (your country) consumer laws..

Most of the “bad” images you will see below are what happens when aDIY attempts to become the importer of LFP batteries.These sorts of issues are almost non-existent  where a decent US company is behind the importation design & manufacturer selection process.

Disreputable sellers will lie and think nothing of it. This LFP cell is 100% made in China……

Always Check with your Insurer First!

The image below is from Markel, one of the largest insurers of boats in the USA.

And here’s an insurance questionnaire/form. Lie on this document and guess what ? You’re not covered!

Important:This insurer wants to see a US company, on US soil so they  have someone to go after should an accident occur. This is why they demand a company based in the US.

Batteries such as Kilovault (MA), Lithionics (FL, Battleborn (NV), Dakota (ND), Relion (SC), Mastervolt (WI), Victron (ME), Trojan (CA), Lifeline (CA) etc. would meet this criteria.

Batteries that come directly from China such as SOK, AmpereTime, Chins, AO Lithium etc. Would not meet this criteria.

There are still many insurers who allow LFP but please check with them first!

What About the ABYC:

If your Drop-in battery cannot meet the underlined criteria (Insert “Strong-Opinion”) you  may want to keep looking:

ABYC TE-13

What About the ISO/ European Safety Standards:

ISO/TS 23625
ISO is Pretty Similar to the ABYC only this standard is active now (ABYC E-13 coming very soon)…

“Rod, isn’t the ABYC is a “voluntary” standard?

Absolutely, but here’s the rub. Every Marina in the United States, and most in Canada, require insurance. If you’re vessel is insured the insurance company has standards they expect. In North America those standards are the ABYC standards. They use Marine surveyors to ensure the boat is safe and up to their underwriting standards. Marine surveyors are currently using ABYC TE-13  as a guide for LFP installations and are actively calling out installations that don’t meet the nature of the TE-13 document.We get emails about this routinely.Our answer is, as always, do as your insurer requests as finding another policy especially if your boat is older can prove to be very difficult..

ABYC TE-13 is currently a technical edition (TE)meaning a technical white-paper defining safe installations. TE-13 will be converting to a full-blown standard called E-13 perhaps as soon as July 2022(could be earlier too). I cannot speak to any of the specifics at this point because I am under an NDA (non-disclosure agreement). Throughout this article I will give some “strong opinions“on what is safe and what is not. You can take from those opinions what you what you want. My opinions will be based on what the final document may look like.

Be Very Careful With the Marketing!

“Marine Grade”

I’m not intending to pick on this manufacturer but it is a good example of where marketing and standards can clash..  Recently a customer emailed us about the new XXX Brand “Marine” batteries, a brand we had never worked with. He is insured by Markel. A couple of days later he sent us this email:

One would think a battery marketed heavily as “Marine Grade” would actually meet the Marine standards?

  YouTube Reviews

I really do like like Will Prowse and I think he’s doing the general public a tremendous service in cutting open all these drop-in batteries and exposing all the dirty little secrets. We too have cut open a slew of these batteries I just don’t do video or video editing well..  The problem I have with Will is that he does not operate in the marine environment and the marine environment is a different set of circumstances & standards than it is for RV or off-grid cabins. For example, I don’t know a single RV that has a 12V bow thruster that can pull over 600A(no load rating) at 12 V and 1600A+for in-rush LRA/FLA rating. An in-rush like this is capable of ruining some FET BMS boards especially after repeated thrusts.

We have had too high a number of readers & a few customers(who self installed) destroy or damage drop-in batteries with their bow thrusters and windlass motors! The good news is that FET BMS’s are getting bigger and more robust all the time so these issues (wimpy FET BMS’s) may soon be behind us…As you can imagine, it gets very, very expensive when you ruin a battery by applying too much in-rush current.. Be careful taking Wills advice at face value for a Marine application is all I’m saying.

Having been asked over and over what “Drop-In” batteries Compass Marine Inc. prefers, likes or That we believe are well designed, the following two brands are where we stand today.

Lithioncs $$$$$$$-Amazing quality drop-in batteries. Built like no other LiFePo4 batteries!

KiloVault $$– These 100Ah, 150Ah and 300Ah 12V batteries are very, very well built for the price point and include one of the most robust BMS’s of any drop-in product we know of. They also use extremely high quality aluminum prismatic cells and each battery has Bluetooth built in for external communication & “visual” TE-13 compliance. Even the busbars inside these batteries are made of Nickel plated copper. Having torn piles of LiFePO4 batteries apart I can say without a doubt these represent one of the best values there is in a 12V drop-in battery.

Is Your Vessel a Good Match for Drop-In Batteries?

Use this flow chart to find out

An upgrade to lithium iron phosphate batteries can always be done in stages. We typically advise starting with the charging system first, as your on-board items become antiquated or become failure prone. We suggest upgrading any sort of charge equipment eg; solar controllers, alternators or alternator regulators with devices that can be fully programmed for lithium iron phosphate batteries in the future.Doing this as the items begin to become failure-prone means that in the future when you’re ready to upgrade to lithium iron phosphate batteries your system will be ready for it.

Let’s Look at Drop-In Battery Specifics:

The popularity of drop-in LFP has literally exploded in the last 2 years. This is good for LFP batteries as a whole, but can also potentially be bad, if the right drop-in’s are not chosen to properly match your vessel.. There are things that need to be considered beyond just “dropping them in“. The term “drop-in replacement” is a very misleading moniker, as these batteries are far from a “drop-in” replacement for lead acid.

Drop-In batteries are most often sold in standard lead acid case sizes eg: Group 27, 31, 4D, 8D etc.. One of the drawbacks to a drop-in battery is that most of them lack any external communication between the internal sealed BMS and the vessel. Currently the 320Ah Lithionics GTX12V320A is the only drop-in marketed battery that offers external communication between charge sources and the battery.

Most of the drop-in batteries have been Chinese in origin, and this is not necessarily a bad thing, if you’re buying from a reputable manufacturer. A large number of the US available brands eg; Trojan, Lifeline, Relion, Kilovault etc. are buying from a hand-full of premium Chinese factories. The difference between straight up US sticker applicators & Trojan, Lifeline Relion, Kilovault and pure US based sticker applicators is that Trojan, Lifeline Relion  & Kilovault designed the batteries and have them built to their specs just like Apple computer does.

Where drop-in LFP batteries often fail the purchaser is in marine specific engineering. To understand why, we simply need to look at the reason these batteries were originally created. Drop-in form factor LFP batteries were originally designed for telephone pole mounting where light weight and “drop-in” replacements for lead acid were critically necessary for the solar powered street lighting & cell repeater industry. The demand for this type of battery, especially in third world countries, is absolutely staggering.

Drop-in batteries were not invented for the use  you think they were

I know many boat owners tend to assume we are a large market, but we are not, and no, many of these drop-in manufacturers are not specifically building marine batteries for us, though they certainly are marketing to us. The application of a “marine” sticker, and perhaps even a well marketed brand name on the plastic box, does not always denote a product that is well engineered or specifically engineered for use on a cruising boat.

Unfortunately, for our industry, many of the “A” graded LFP cells used in the plethora of Chinese drop-ins, are sold into the street lighting or EV market industries. Please understand that the term”A” grade is really a meaningless-term in China. “A”grade really means EV grade but the Chinese have figured out that people think “A”grade actually means something…It may actually mean “A”bhorrent grade” depending on who you buy from

For boaters buying drop-in batteries direct from China this can mean the low-grade “orphaned” or “rejected” cells wind up in batteries that may look exactly the same but are sold on Ali-xxxx, , eBay or through other less reputable sources.. Once the cells are sealed in its glued together plastic case you the buyer have no way to know what quality cells you got.Below is an example;

Direct from China FAIL! This battery came directly from Aliexpress:

You may ask yourself why I say take Will Prowse reviews with a grain of salt? This image explains exactly why I say that. I have yet to see Will’s reviews include a discharge capacity test of each individual cell in the battery. I know darn well why he does not do this …. Time.. We use the exact same computerized capacity tester Will does, plus a few others, but this stuff takes time, lots of time. The problem with this Aliexpress battery is that the cells had a 8.3% variance in their Ah capacity! This battery tested at 100% capacity on cycle #1. On the recharge is where the problems showed up. As a result there was no way this particular BMS could ever keep the cells in balance. The bottom line is this battery was built from reject /grade B cells that never should have been in a battery that was marked or sold as “A” grade! We’ve done lots of testing for viewers of Will’s that confirmed the cells or battery they got from Aliexpress were not actually A grade or EV grade cells.There are not many companies capable of doing this testing, so this has meant quite an in-flux for us in the last few years.

Sadly Ali-xxxxx has literally become the numero-uno dumping ground for reject LFP cells and batteries from the Chinese factories. They get away with this because they know the vast majority of buyers have no way properly to test them once the battery case is glued together. Frustrating? You bet it is! Always buy your LFP batteries from reputable companies not directly from China unless you love to gamble.

The internal BMS in this battery was completely incapable of balancing the cells & one high cell kept tripping the BMS on high voltage. 3.65V is the maximum safe cell voltage for a LiFePo4 cell (the image above has two cells in the danger zone). We spent about two hours reprogramming the BMS after multiple emails back & forth with the manufacturer who refused to give us the BMS passcode so we could custom program it to make it work better for poorly matched cells. We then tried to charge it and to get the cells balanced for three straight days. Nothing we did could balance the cells so this battery would not trip the BMS on cell high-voltage.Please note the recommended charge voltage was 14.6V and even at 14.2V we have two cells well into the danger zone.

The customer finally gave us the okay, after emailing with the manufacturer,  to open the battery and test each cell individually. This required the complete destruction of the battery case because it had been glued together with what appeared to be superglue. The only way to get open was to cut it open. When we finally capacity tested the cells it was discovered that there was an 8.3% variance in cell to cell  Ah capacity on these four 100 ah cells.There was no way this BMS was going to keep up with that variance, balancing wise.

Once the manufacturer had the testing data they then backpedaled on the warranty and refused to take battery back because the battery had been cut-open(which they had said was ok). The customer was out all the money he spent on shipping plus the battery costs direct from China(His take was that as an Aliexpress buyer you have no rights and no recourse). He was also-out  about $380 in labor for our shops testing costs. In the end he wound up buying two KiloVault batteries and has had zero issues since..

Drop-In LiFePo4 – Important Points to Consider:

 BMS Current Handling 

The current rating of the internal switch that protects the battery is quite often too small for the task on many cruising boats. Drop-in LFP batteries routinely use multiple tiny little MOSFET switches as the batteries BMS protection ON/OFF switching. Unfortunately these FET’s often can’t handle the typical loads imparted by many cruising boats. On board devices such as bow thrusters (400A +), windlass’ (100A to 300A+, large inverters 150A to 300A +, electric winches 75A to 300A +, electric cook tops, massive alternators, chargers or large inverter-chargers are very very common on-board cruising boats these days. These are exactly the devices many boat owners are hoping to see a gain in performance from when switching to LiFePO4.

This is what a 120A rated FET based BMS looks like it is pretty for a typical 100Ah drop in battery. This is what an internal FET based BMS boards typically looks like with the heat sinks removed. The blue wires connect to the neg end of the cell string and the black wires are connected to the external negative battery post.fet bms’S DISCONNECT ON THE NEG SIDE OF THE BATTERY This one uses two 10GA wires for its 120A continuous rating. All 120A has to pass through those two 10AWG wires, the printed circuit board and the FET’s. The hotter FET’s run the shorter the MTBF (mean time between failure) is. This Particular BMS ,a JiaBaida, uses 32 FETS(the board has double sided FET’s.  We have cut open drop-in batteries with 100A rated BMS’s ( that use only 10 FET’s.(see image below this one)..

What a FET BMS Looks Like

The Miniscule BMS below came out of a customers AliExpress  drop-in that was sold as a 100A continuous BMS. It was also sold as Hot and cold temp protection. As can be seen the temp sense port(only one port not two.) is not even soldered to the BMS’s PCB. Hard to have hot and cold BMS protection when the sensor ports are not even installed. These are the “Lies” we talk about when flying solo and ordering directly from China..Oh and this was wired to the batteries neg terminal with 12AWG wire…! 12AWG/100A!

Do You know the quality of the FET’s ?

What if I have High-Current DC Devices?

If you own a vessel with high load devices, do yourself a favor and look at the contactor ratings (the BMS protection switch) that “marine specific” companies such as Lithionics/OPE-Li3, & Mastervolt use for their”marine specific” LFP batteries. What you’ll often see is a 500A continuous rated Gigavac, Blue Sea ML-RBS, Tyco EV-200, or in the case of Lithionics, military grade 500A contactor/relays are being used as BMS protection switches.

Compare that to some of the drop-in batteries being sold out there which can have relatively low-current handling capability due to the use of often under-designed( for a cruising boat)FET based switches. The manufacturers building “marine specific” batteries eg; LFP Mastervolt OPE-Li3, &Victron know what a typical cruising boat needs in terms of current handling and they engineer this into the product. Does this mean you need to use a “marine specific battery? No, it does not it just means you need to choose your drop-ins very carefully for your vessel.…

A Dead FET BMS (windlass in-rush)

Below is the BMS “switch” used by Mastervolt on their MLI series LiFePO4 batteries. It can handle bow thrusters, large windlass motors, massive inverter-chargers, massive alternators. etc.. The ML-RBS  switch is rated for 500A continuous, 700A for 5 full minutes and 1450A for as long as 30 seconds. While many smaller boats can often get by with a FET based BMS, not all boats will, so please consider the max continuous discharge and recommended charge ratings of the battery you are purchasing. This rating is not usually limited by the cells but rather the internal BMS’s current handling capabilities.

Let’s take a look at the BMS switch Mastervolt  uses. (Lithionics uses a similar switch on their external BMS batteries.

You read that correctly; 500A continuous or 1450A for as long as 30 seconds!!!

Sadly, when buying direct from China,you can still find diminutive 50A continuous rated FET switching BMS’s installed inside a 300Ah LFP battery. As a comparison a 150Ah KiloVault can handle 150A continuously or 200A for as long as 30 minutes. While a 50A rated BMS may be fine for small boats,  if you have large on-board DC loads, or want to charge a 300Ah battery quickly, then a battery like this is going to be a less than ideal battery for marine use. So, you still really need to do your homework to make sure the batteries & the internal BMS are a fit for your vessel.

Building a Drop-In Bank to handle Large DC Loads

When it comes to FET based BMS batteries we typically advise smaller individual batteries, wired  in parallel. This is done to share the load across the FET based BMS’s. For example three 100Ah / 1C rated LFP drop-ins can theoretically handle a 300A discharge, if the parallel wiring is perfect and all batteries share the load equally(rarely happens that way.) A 300Ah 8D format drop-in, like the one addressed below, can really only handle a 100A (0.33C) discharge. When in doubt with FET based BMS systems smaller batteries in parallel are usually a better solution than one large battery with a low current rated BMS.

You Need to Read The Specs Carefully!

Purchase FAIL!

Sometimes one just has to laugh when reading the specification sheets on some of these direct from China drop-in batteries.

This drop-in LiFePO4 (LFP) battery is rated at 12V-300Ah with a maximum charge current of just 50A!

A 50A max charge current on a 300Ah battery is a charge rate of 0.16C

0.16C IS A LOWER CHARGE RATE THAN A FLOODED LEAD ACID BATTERY CAN HANDLE

The specification also claims 2000 100% SOC to 0% SOC cycles, not too dis-believable for LFP. However they then claim 20,000 cycles at the end of the spec! This is at least double what any reputable LFP maker claims! It then claims “fully charged in 60 minutes“.

“Fully charged in 60 minutes” Holy $hite, that’s fast, but just to be safe, lets do the math..

300Ah battery at 0% SOC – 300Ah / 50A = 6 hours –Fail

300Ah battery at 20% SOC – 240Ah / 50A = 4.8 hours –Fail

300 Ah Battery at 83.4 SOC – 50Ah / 50A = 1 hour –Winner

You read that math correctly. The only way we you can get this battery to charge in 60 minutes is if you only discharge to 83.4% SOC……. So much for those deep-cycling &  “fast charging” LiFePo4 batteries? My point here is to help you learn to dig deeper into the specs so you can learn to spot bogus claims.

If you’re less than educated on a subject, drop-in battery makers will try to sell you anything you want to believe. Educate yourself and do the research

Another Purchase FAIL!

The image below is a prime example of how boat owners, without enough knowledge, can get burned buying LiFePO4 batteries. We were consulted by an owner who purchased a 300A drop-in battery from what he thought was a “reputable manufacturer“. During the transaction, he had no consultation with the manufacturer and no questions were asked by the re-seller. He just ordered it based on it’s “8D drop-in” format, the claim that it was an exact drop-in replacement for his lead acid Lifeline 8D battery, and the 300Ah capacity rating.

He felt comfortable because it was, what he considered, a “reputable manufacturer” and they are based here in the USA. He quickly destroyed three alternators and the BMS kept disconnecting when he was inverting with his large 3kW inverter/charger. The BMS disconnecting while charging also damaged his inverter/charger. When I pulled up the spec sheet on the 300Ah drop-in battery he’d purchased, the problem became crystal clear. It is highlighted in yellow below….

You are reading that correctly, this massive 8D form factor LiFePO4 battery was only capable of a 100A discharge and a max short duration charge of 100A. To keep the BMS cool, and the cells balanced, the manufacturer has a “recommended” charge rate of just 15A to 50A for a 300Ah battery. This 15-50Ais not a limitation of the cells inside the battery it is a limitation due to the FET based BMS that is used to protect this battery.

PURCHASE FAIL! For this particular application this drop-in was a horrible fit. A fault of the battery? No, not at all. This was a shared failure in the marketing, the retail chain, and of the owner. I partly blame the owner here because he failed to do the research and fully comprehend the specifications of what he was actually buying. Of course who can blame him when these batteries are boisterously marked as “drop-in replacements“. As can be seen from this example these are ABSOLUTELY NOT drop-in replacements for a lead acid 8D battery as his Lifeline 8D’s never once disconnected themselves from the alternator or the inverter…

What EVERY Drop-In Battery Spec sheet SHOULD Look Like

*Highlighted specifications are the critically important ones.

High Voltage Disconnect (HVD) Cut-Off Protection: This is critical to know because it is the voltage at which the BMS will disconnect the battery from the vessel.This is usually specified on a per cell basis. So a 3.65V disconnect on a 12V battery would be 3.65V X 4 cells=  14.6V BMS Disconnect Minimum Absorption Voltage (to Initiate Cell Balancing): This is important because you need/want to activate balancing with each charge cycle. You also want to avoid pushing to the maximum charge voltage every cycle if you wish to maximize cycle life. Maximum Absorption Time: Again, This one is critical to cell longevity. If it suggests a maximum absorpyion duration of 30 minutes you had better make sure all your chargers can be programmed not to exceed this.. High Internal BMS Temperature Charge Cut-Off- This is one you have little control over other than to not push your BMS near the charge-current limits. It is always best to charge at no more than the “recomended charge-current. 95% of the load-dump damage we’ve seen is not due to high voltage cut-offs but rather from a BMS disconnecting due to BMS Temp. Be Sure your manufacturer specifies This!

High Internal BMS Temperature Discharge Cut-Off:  same as above but for discharging. Delay until Peak Discharge Overcurrent Protection Cut-Off: This spec, from a reputable manufacturer ,will almost always be followed by the millisecond rating (ms)before disconnect eg:320A 8ms This would mean the BMS will disconnect if it sees 320A for 0.008 seconds or more. This is why knowing the in-rush draw of all DC Motors is critical before installing LiFePo4 drop-ins. Recommended Continuous Charge Current: Always follow this guidance not the “max charge current.The reason for this lower number is to keep BMS temp down and to allow balancing to keep up. Many of these BMs’s only have 20-390mA of balance current to work with! If the celllsget out of balance & you are fast charging the BMS may never be able to keep up!! Maximum Parallel Configuration : (Identical Model Batteries): Do not exceed this number! Maximum Series Configuration:(Identical Model Batteries):Do not exceed this number!

If you are unfamiliar with what the specifications mean or why they are critical you may want to reconsider drop-in batteries until you have completed the research phase.

Vibration

Many of the very cheaply sourced drop-ins are using 18650, 26650 or 32650 cylindrical cells inside the battery case. In a worst case, a 100Ah LFP battery, built from 18650 cells, would need a grand total of 364 cells with two connections per cell.

Hows that math work?

18650 Cell = 1.1Ah (typical Ah rating for an 18650 LFP cell)

91 Cells Make Up Each 3.2V cell

Four 3.2V Cells Make Up a 12.8V 100Ah Battery

91 X 4 = 364  18650 Cells

Positive & Negative Connections Inside The Battery = 728

If the manufacturer uses 5Ah 32650 cells, and some do, we then only need 80 cells total, and 160 spot welds or bolted connections to potentially fail or work loose. (32650 cells are available in bolted or spot weld versions)

The connections, with 18650s’s, are almost always spot welded to end boards that make up the individual cells.  So, in a single 100Ah battery, made of 18650’s, just to connect the cells, we have as many as 768 spot welds to rely on. Beyond that we have all the internal wiring and BMS connections. These spot welded assemblies are often just dropped into the polypropylene case with no other support or vibration dampening material.  To be safe, always be sure to ask the battery supplier to furnish third party vibration testing results or testing to UL or IEC vibration standards.

A Look at the BAD of LFP:(most of these images are “direct fromChina” purchases).

Do you suppose this Rube Goldberg level Ali-xxxx LiFePO4 drop-in battery manufacturer, and I use the term "manufacturer" sarcastically here, has paid to have this battery vibration tested?
                                 Image courtesy MHT Reader

No  Not Kidding!

                                                     Image courtesy MHT Reader

Heck the guy assembling these cells, most likely in his mom’s spare bedroom, can’t even solder well or use a spot welder with any level of quality or precision. Vibration testing? Only if they are flat out lying about it. Purchasing LFP anything on Ali-xxxx is a very strong buyer beware!

This LFP”starting battery” has NO BMS Protection!! Balancing only!!

                                                                     Image courtesy MHT Reader

Starting a 44HP Westerkeke takes…….640A!!!!

What’s Wrong here?

OK, I’ll Help Out.. Look closely at the series connection below!!!!

An 18650 cylindrical-cell battery failure

How did we discover the spot weld failures? The zipper like discharge graph was a dead giveaway..After a discussion with the manufacturer we had to tell the customer to stop using his bank immediately…It had also lost significant capacity from over charging.His lead-acid charger that held 14.6V way too long. We were testing them for capacity when we discovered the spot weld failures (brand purposely obscured). In the screen grabs below you can see how varied the voltage was on discharge.We had wanted to run the discharge at 40A but the zippered graph was even  worse at 40A so we ran the capacity test at 10A..

Data point =12.582V

Data point = 12.702V

What happens when you cram multiple small wires into one terminal and ask them to carry 100A +/-Hint: You get terminal melt down..

And here’s what they look like when you hit them with thermal imaging.

This is the level of “quality” you may find inside that beautiful plastic case

Because you can always trust the sticker on the outside of the battery

More Direct from China misleading BS

 

A FET  BMS has aluminum heat sinks because it needs cooling. Stuffing it in-between foam blocks is well…… not a wise solution.

But, some dude on the Internet said LiFePO4 is 100% safe…..

No battery chemistry is 100% safe, especially when you over charge it.(However no-fire , no-flames & no explosion just cell swelling and heating… FWIW this “starting battery” has zero BMS Protection!!

                                                                        Image courtesy MHT Reader

Do you know what horrors are hiding in that”direct from China” plastic box?

The Battery Below(image5) is typical of the Quality you’ll often find on Amazon or Aliexpress. So, what happened?

1-BMS is Catastrophic protection only. If a BMS allows cells to charge beyond 14.6/3.65VPCWalk away!!

2- BMS Allowed cells to hit 15.6V /3.9VPCbefore disconnecting!max safe cell voltage is 14.6V//3.65VPC

3- Cells were not in a case that provides cell compression to limit cell swelling

4-Cells balooned and split the battery case open- Battery ruined.

Aluminum Prismatic Cell ruined by over-charging

*image5– Cells ballooned/swelled  due to over charging. This BMS was catastrophic protection only and allows the cells to hit 15.6V before the BMS disconnects (this is enough to ruin the cells and totally brick the battery)

This what proper cell compression for prismatic cells looks like looks like! Has your chosen manufacturer included this?

The “Bad”images above are a reality of what you can often find buying your batteries directly from China without a reputable company insulating you from these horrors…

One last warning about buying direct from China

What Better Quality Looks Like

Compare the above cell block from Ali-xxxx to the photo below of a Lithionics g-31 drop-in battery. This battery uses impeccably matched aluminum encased 5c LiFePO4 cells. The cells are fixed in place by an injection molded jig that protects them from movement and vibration failures. The busbars are high grade nickel plated copper and self locking flange/wizz nuts are used to hold the cells to the busbars. The BMS used in this battery is certainly FET based but it is made here in the USA, of Mil-Spec components, and is designed to handle starting engines. There is a huge variance in the quality of LiFePO4 drop-in batteries. Yes, this battery is more expensive than a 100% Chinese made drop-in, and they are only sold after a consult to ensure they are the correct fit for the vessel. Bare minimum alternatives to the Lithionics would be the KiloVault HLX Series. A lot of folks swear by Battleborn but the Battleborn batteries to not yet meet ABYC requirements for E-13.E-13 will be official in about 60 days from this article being published.

Internal Wiring 

It is not uncommon to open a 100Ah drop-in battery, rated at 1C, and find a single 10GA or 12GA wire feeding the main positive and negative terminals. When someone finds a 10GA or 12GA wire rated for 100A, under any safety standard, please let me know?

This is how Lithionics does it on their 4D 320Ah drop-in.

BMS Shortcomings -Lack of low or high-temp Protection

Some of the drop-in batteries may lack  BMS temp protection altogether . Drop-in batteries should have both low and high temperature protection (a requirement for both ABYC and ISO) but many don’t. Far too many drop-in batteries lack low temp protection and a large number of manufacturers who claim it has low temp protection are actually lying about it. If  You live up North,buyer beware!

Non-Communicable BMS 

This one is perhaps the most frustrating aspect on-board a cruising boat. For a trolling motor, who cares? It’s not powering anything critical. For a house battery, on a cruising boat that ventures off-shore, and is powering critical navigation and safety equipment, this can create a dangerous situation. A non-communicable BMS is one that can not communicate externally with the vessels charge and load systems, or even you the owner. It has no means of externally communicating or sending/sounding warning alarms or activating relays/triggers to properly and safely disconnect charge sources or give ample warning of an impending BMS disconnect. Some batteries are now featuring Bluetooth monitoring but this still requires you the owner to be watching it.

Let’s take a look at one of the worlds most respected marine standards for shipping etc., Bureau Veritas.

As can be seen, under Bureau Veritas standards external communication between the battery and the rest of the systems such as charging is a requirement. For why see below.

WHAT ABOUT CHARGING?

LFP batteries are charged using a CC/CV profile. This means constant-current/constant-voltage

Bulk = Constant-Current(charge source working flat out  or as hard as it can)
• Absorption = Constant voltage( voltage is held steady for a short time or until current declines to the manufacturers spec.
• Absorption Duration = Once the batteries have achieved the absorption voltage the time the batteries spend  at this voltage must be limited. Many lead acid charge sources spend far too long in absorption and this is not healthy for LFP

BMS LOAD DUMPS

DON’T FORGET YOUR ALTERNATOR

Email from MHT Reader:

“RC,

The alternator for the Volvo MD2030 with 300 Amps LiFePo4 14.6 max lasted a few hours. I believe BMS was switching on to off  I to keep theLiFePo4 voltage to safe measure? Boat service replace alternator and it happens the second time? I now read your story on lfp and it explain to me why.”

Unfortunately the reader above learned the hard way. Ask yourself what happens when your alternator is in bulk charge, supplying all the current it can, and the internal BMS decides to “open circuit” or disconnect the battery from the boat? I’ll help out a bit here.

BMS load dump illustration
What a voltage transient looks like:

The load dump transient captured in the above image is from an ISO test of a 12 V automotive alternator. Of important note is how quickly this transient surpasses 90V. The transient surpasses 90V in just 0.01 seconds!

   A) The alternator diodes, unless avalanche style, (rare in many existing marine alternators) but all Balmar alternators now use them, can be blown and the alternator can be rendered non-operable. Two years ago we  did exactly this. Using the alternator test bench here at CMI the 90A  alternator was running at full bore charging an LFP battery. The “system” I set up had a .3A dummy load on, light bulb, to simulate a depth sounder. With the alternator running at full bore I disconnected the battery, just as an internal sealed BMS can do for BMS temp, cell diff-voltage or cell high voltage. Poof went the alternator diodes and the light bulb was burned out instantaneously! Worse yet the voltage transient I recorded on the “load bus” (think your navigation electronics) using a Fluke 289 was 87.2V. Ouch. Even if your alternator uses avalanche diodes, like Balmar’s do, the voltage at which they begin to protect the alternator is far too high for the vessels load bus equipment so you still need a way to protect against a load dump.

   B) If the boat is wired, as is typical with drop in batteries, the voltage transient caused by the open circuited alternator will now directly feed the DC mains and potentially destroy your navigation equipment.

TIP: At a bare minimum, every drop-in LFP battery bank, that can be charged via an alternator, should be installed with an Alternator Protection Module!

The Balmar Alternator Protection Module is an inexpensive insurance policy against a BMS load dump destroying your alternator. If you can afford to purchase drop-in LFP batteries you can also afford to protect your alternator from a BMS load dump.

A well designed marine specific BMS would open a relay that can de-power your charging sources on the input side, thus shutting the charge sources down correctly and safely with no risk of a damaging voltage transient. For a large inverter/charger it would de-power the AC input side, for an alternator it would de-power the field wire or regulator B+, for solar it would open a relay in the PV feed etc. etc.. With a drop-in battery, that features a sealed BMS, you have no way to do any of this. Only Lithionics Drop-In Batteries have this Capability.

But Rod, I plan to program all my sources below the BMS disconnect voltage.

Sounds like a good plan right? Well, lets examine the reasons a BMS can disconnect

This image sums up why programming a lower charge voltage cannot always protect against a BMS disconnect.

Are  BMS Load Dumps Real?

I’ll  let Balmar Explain this;

How about a fairly knowledgeable owner who bought a very beefy alternator and still killed it due to BMS load dumps.

Drop in batteries with the exception of Lithionics do not have a way to properly shut down the alternator before the battery disconnects. For this reason we need work arounds..

The number one reason we see batteries shut down(when everything is programmed correctly) is almost always due to BMS temp related issues not necessarily  high cell voltage..

A good technique to mitigate load dumps is to keep a buffer “load” on the charge bus at all times (Buffer load = lead acid battery on the systems charge bus see FET Isolator wiring below). With FET isolators we like to see them at least double the rating of the alternator eg; a 200A ARGOFET for a 100A alternator. The cooler FETs run the longer they last.   And yes, we have seen FET isolators fail…

Load Dump Work-Around’s

Using Low Volt-drop FET Isolators

Using Low Volt drop FET Isolators

USING DC to DC CHARGERS

There are many benefits to using DC to DC chargers. One of those benefits is that the charge profiles can be custom configured to charge lithium iron phosphate batteries where your factory alternator or legacy lead-acid charge equipment cannot be programmed for this. The Victron and Sterling power DC to DC chargers can also absorb a load-dump from a BMS disconnect where your factory alternator cannot.

However, caution needs to be used when sizing DC to DC chargers. A DC to DC charger should be sized at a maximum of 50% of the factory alternators rated output. This means if you have 100 amp factory alternator the maximum DC to DC charger you should use is 50A. This will help keep the alternator cool and keep it from burning itself up. Currently there are only two DC to DC chargers we recommend and those are Sterling Power and Victron.

The only drawback to using DC to DC chargers is that you give up charging your lithium ion phosphate batteries quickly. Seeing as that is one of the major benefits of  LFP batteries we would strongly advise considering an externally regulated alternator with an external regulator  such as the BamaMC-618 or Wakespeed WS-500these regulators can be programmed for LFP and have an alternator temperature sensor to protect the alternator from heat damage. This will also result in considerably faster charging!

Caution:I don’t often do this as I hate to ever advise against any manufacturer but there is one manufacturer that we would urge a very strong caution on and that is Renogy. We’ve not seen a manufacturer with this many failure prone products in 30+ years in this market. Their failure rate is far too high for us to even consider making a recommendation. Consider yourself warned about buying Renogy.

You can read about  DC to DC Chargers HERE.

WARNING:Do not size a DC to Dc charger at any more than 50% of your stock alternators rated output!

The drawback to using DC to DC chargers is that it results in SLOW LFP charging

Using a Victron Orion TR Smart DC TO DC Charger (Be sure it is not the Orion TR- it must be the TR SMART)

CAN I USE MY STOCK ALTERNATOR?

The short answer is we do not advise this for charging lithium iron phosphate batteries directly.You can however use your stock alternator if i it is behind a DC to DC charger that serves to protect it and that provides the proper charge profile for the lithium iron phosphate batteries.

WHY?

1-A stock alternator rarely has the correct charging voltages for lithium iron phosphate batteries.
2-They can over absorb the batteries resulting in over-charge damage
3-The absorption voltage is very often too high (see below)which  can lead to BMS load-dumps
4-Stock alternators do not FLOAT, they only do bulk and absorption.
5-Alternator heat damage

Do You know the voltage set point of your stock alternator?

Please understand that we have been an alternator manufacturer for more than 15 years so we understand internal vs. external regulators and how these alternators are built. We also have access to data, such as you’ll see below.This is data the average DIY would never have access to.

The max charge voltage for any drop in LFP battery is 14.6V(some are much lower). Below is a sampling of common internal voltage regulators. Pay attention the voltage set points!

 IF your BMS Disconnects at 14.6V / 3.65VPC a reg with a 14.6V set-point is likely to cause you BMS disconnect issues.

These are the most common regulators found in the very popular Delco 10/12Si series Alternators

There is also the Potential for Alternator heat damage!

LFP batteries have a tendency to enjoy eating alternators for lunch. The internal resistance of LFP batteries is extremely low resulting  in very long bulk-charging times. As a result alternators can burn themselves up trying to charge these batteries. I’ve said this many times before on the site and I will say it once again, there is no such thing as a small frame alternator that is continuous duty, I don’t care who built it!  Because Compass Marine inc. is a manufacturer of marine alternators so we get to see these failures regularly. We are not an n=1 data point like the “dude on the internet” who says your stock alt will be fine charging LFP. We have seen far too many alternators completely melted down by LFP batteries to ignore this information..

If you insist on using your stock alternator we would strongly recommend that you put it behind a DC to DC charger (50% smaller than your alternator amperage rating. This will help limit the amount of work the alternator is doing and protect it from a meltdown.Doing this means you can continue to use your stock alternator.

If you expect to charge lithium iron phosphate directly from the stock alternator without a DC to DC Charger in-between, we advise not changing a thing. Do not increase the wire size  to the battery bank ,do not move the volt sense a wire do not touch the factory wiring .zDoing so can result in an alternator meltdown. The typicalfactory wiring on these alternators is horrible and results in a lot of voltage drop. That in and of itself can help protect your alternator from melting down.

Why does LFP cause heat damage?

It is very simple your alternator never catches a break!

Our assembly bench on a typical day..

Don’t be this guy!

ImageCourtesy MHT reader

This stock Yanmar/Hitachi alternator was destroyed in a matter of weeks with just three 100 amp hour drop-in batteries.

Another burned up stator from charging LFP

Oh crap another one!

Jesus H…..! Another LFP Cooked alternator

But Ample built good alternators? Yes, they did but during this vintage Ample Power did not believe in using an alt temp sensor on their regulators.. When LifePO4 came around…Toast!

Series Wired Systems ?

In a parallel wired bank one battery BMS dropping out only creates problems when it re-engages into a different SOC than the rest of the bank by causing a large in-rush. With a series bank (for 24 V 36v or 48V a single BMS taking itself off-line spells disaster at sea and takes out the entire bank. I know a Drop-in owner who hit a granite bridge abutment in his electric boat using a 48V series bank of drop-in batteries. It did a few thousand in damage to the boat, and his pride, but it could have been much worse. The owner had zero warning the battery was about to disconnect itself before he lost all propulsion power. This failure occurred going under a drawbridge in a very strong tidal current. This is but one reason why the ABYC & ISO European standards make sense. Kilovault will soon be out with a communication system for series wired batteries so they stay in balance.We do not advise series wired drop-in batteries unless the BMS’s can communicate with one another. Parallel batteries stand a much better chance of remaining in-balance, series batteries do not unless the BMS boards can communicate with one another.

CATASTROPHIC PROTECTION BMS VS. CELL HEALTH PROTECTION BMS

Please don’t assume every drop-in battery BMS will manage your battery for maximizing cycle life, it may not do that! The BMS in far too many drop-in batteries is designed for catastrophic level protection only. Catastrophic protection means the BMS is only there to protect the cells from thermal run-away conditions. They can have BMS disconnect voltages exceeding 15V for a 12V nominal battery. The max safe cell voltage for an LFP cell is 3.65V X4 cells = 14.6V max. It is up to you, the owner, to ensure the battery never exceeds a safe operating envelope  even if the BMS allows for this. Well built drop-in batteries use an internal BMS that actually protects the battery from a maximizing cycle life perspective. Batteries built to maximize cycle life will have much more conservative HVC and LVC voltage levels.

TheBMS on this battery is built to maximize cycle life:

Never purchase a drop in battery that allows the cells to exceed 14.6V/3.65VPC or that disconnects below 10.0V/ 2.5VPC

#9 Understanding Cycle Life Claims – When an LFP cell manufacturer rates a cell at 2000 100% DoD cycles this is; charge to target voltage, stop immediately once you hit that voltage, discharge to the low voltage threshold, repeat, repeat, repeat. If this target voltage for cycle life testing is 14.6V they charge to 14.6V, stop immediately and discharge. These cells, at this rating, are not held at a the target voltage for cycle-life testing. In other-words you may not get the claimed cycles using a lead acid charger that holds an absorption cycle timer orcharges differently than the way the cells were tested.

WHAT ABOUT CHARGING LFP WITH OTHER SOURCES?

LFP batteries are charged using a CC/CV profile. This means constant-current/constant-voltage

Bulk = Constant-Current(charge source working as hard as it can see burned up alternators above)
• Absorption = Constant voltage( voltage is held steady for a short time or until current declines to the manufacturers spec.
• Absorption Duration = Once the batteries have achieved the absorption voltage the time the batteries spend  at this voltage must be limited. Many lead acid charge sources spend far too long in absorption and this is not healthy for LFP.

Do you know what this means?

max charge voltage 14.6V

max charge current 20% of installed Ah Capacity

When at 14.6V all charging must stop when accepted charge current has dropped to 0.02C or 2% of installed Ah capacity

Can Your existing charge system do this?

Pay attention to the details!

When installing these LFP batteries in parallel the max charge voltage is just 13.8V-14.2V   (it’s 14.6V for a single battery”details”)
Max charge current is 50% of installed Ah capacity or .5C.
When at 13.8V – 14.2V and charge current has fallen to 5% of installed Ah Capacity all charging MUST STOP

Can Your chargers do this?
Can Your charge sources be programmed for these parameters?

*Drop-In Charge Voltages – Follow the manufacturers guidance!

Some drop-in batteries are not using cells that are impeccably matched. Lithionics would be an exception to this rule but they are obviously a lot more costly.

Unfortunately, with most “drop-in” batteries you don’t really know what is inside, or how well matched the cells or cell blocks are. You’re essentially shooting darts with a blind fold on. Lithionics and Kilovault are in a very small group of manufacturers that take quality & cell matching to the level it should be. Lithionics can actually supply a performance test sheet for every cell in their drop-in batteries.  Battheborn matches individual cell modules(they use cylindrical cells) but not each cell in a module.

Series Solar Warning!

Over the last few years on boats one of the trends that can be a little terrifying has been that solar panel array voltages have been creeping up and up.. Many boat owners want to install their solar panels in series and then run them through an MPPT controller to maximize the energy capture of the array.

This is all well and good until there is an issue and the MPPT controller fails. Imagine what happens if you’re MPPT controller fails and starts passing PV voltage through to the batteries? If your array is over 60V & these are lead acid batteries they will eventually explode. If they are lithium iron phosphate drop-in batteries you will toast your BMS! Once the BMS is been fried by the solar array voltage you have no BMS protection & the solar array will continue feeding dangerous voltage to the batteries until they are destroyed. You can imagine what will happen if this continues to go on after in an MPPT failure. In case you’re wondering yes, these failures have happened and lithium iron phosphate batteries have been destroyed due to this. These failures almost never occur in tier-top tier supplier MPPT’s.

How do you avoid this?

#1-observe the maximum number of series batteries you can wire for. With most brands limit this is 24 V or 48 V. This voltage is typically the maximum SAFE voltage the battery bank BMS CAN handle. So, your PV array should not exceed this voltage.

#2 if you wish if you wish to use series-solar on your vessel you will be safer to split the array into smaller series strings that remain below the batteries maximum series allowable voltage and give them each their own MPPT solar controller.

#3 Use only top tier MPPT suppliers (eg; VICTRON, OUTBACK, MIDNITE, MORNINGSTAR ). These controllers use isolated input/output and  are designed not to fault in a manner that passes full PV voltage through to the batteries..

*Pack Voltage vs. Cell Voltage:

Pack voltage tells you nothing about cell voltage as can be seen below!

Know your loads before you buy!

The critical load data you need to know is the in-rush current for all DC Motors .This includes a windlass, electric winches or a bow thruster. You also want know your inverters Pre-charge in-rush.  Unfortunately most DC Clamp meters cannot properly capture DC in-rush current. We own three DC clamp meters that claim to do in-rush but all except the Fluke meters fail miserably. The image below is one of our Fluke 376 meters capturing the in-rush current for a Lewmar V2 Windlass. This customer ruined his FET BMS (seen in an image above in this article) byusing his “direct from China” drop-in battery to power his windlass. Warranty? Ha-ha now that’s funny….

The image above is a prime example of how drop-in battery bank went wrong for this customer. he wanted to lighten the load in the bow of his sailboat so he installed a single drop-in battery to power his windlass.What he failed to understand was the BMS’s current handling rating . In just a few short weeks he destroyed his drop-in battery with his windlass when he failed to account for what the peak in-rush current handling of the BMS., Warranty? Not covered!

1) Balance current-The sealed internal BMS’s in most drop-in batteries don’t have a lot of balance current to work with, usually mA level currents for balancing. We have even seen some BMS specs suggesting they can only balance the cells at a maximum 10 – 30mA or just 0.010A to 0.03A.If you’re running a 200 or 300Ah @12V battery the cells had better be well matched or the BMS may not be able to keep up….Again, Only buy from reputable Vendors!

2) Ballancing –Ballancing Does not usually start until the cells are exceeding 14.4V or 3.6V per cell. Some are slightly higher and some slightly lower, just depends upon what you bought. Where the cells begin balancing MUST always be specified!If you don’t see this spec ask the manufacturer.. This means that in order to ensure the cells stay in balance they need to get to a balance level at each 100% SoC charge cycle. The reason drop-in makers suggest such high voltages is because balancing is typically done at the top-of charge with a FET based BMS.  KiloVault batteries begin to balance at 14.0V(pack) or 3.5VPC.This is is excellent for cell longevity and iswhy Kilovault can claim 5000 cycles @ 80% DoD….

3) Absorption Duration –The manufacturers, for obvious reasons, want a short absorption voltage duration, some as short as just 2 minutes but many demand less than 30 minutes. With mA level balancing current, two minutes is not a lot of time to re-balance cells so they depend upon the battery getting to the balance voltage with each excursion to 100% SoC. If it does not get to a balancing voltage, the battery cells can become out of balance and the FET BMS may never be able to catch up with out of balance cells..

WHAT YOU WANT TO LOOK FOR IN A DROP-IN?

#1 Externally communicable BMS; at a bare minimum Bluetooth FOR ABYC  “VISUAL”COMPLIANCE.

#2 BMS current handling(in-rush data): You’ll need an internal BMS  capable of handling the amperage’s found on your  boat. If you’re vessel has large DC loads such as electric motors powering winches a windlass or a bow thruster you need to carefully confirm that the drop-in batteries you’re buying can handle these loads. The proper measurement of these motors is not the wattage rating it is the in-rush-current.

 #3 UL Testing -Bare Minimum=Individual cells that have passed UL testing

#4 Third party vibration testing data – UL, IEC or equivalent vibration testing for the entire battery, not just the bare cells

#5 Verification of internal cell matching. Currently Lithionics is the only drop-in battery manufacturer I know of that can physically send you the cell matching testing data for each cell in a battery. With only the batteries serial number, Lithionics can print this report and send it to you. This is the type of data that every drop-in battery maker should be able to provide.

#7 Internal wiring gauge & temp rating specifications

#8 External BMS alerts that can externally warn of a trend towards a disconnect.(Both an ABYC and ISO Requirement)

#9 BMS low voltage, high voltage and over & under temp protection for each of the four 3.2V cells in the battery

 

 

Legitimizing LFP

It’s not just the Chinese who realize they can grab market-share with LFP. After having their “deep cycle“clocks cleaned by LFP, both Trojan and Lifeline battery, two major lead acid players, have entered the LFP market. Having actual lead acid battery manufacturers in this marketplace actually lends credibility to LFP. These manufacturers can no longer ignore it as they have dug their own graves by misleading customers about cycle-life. The manufacturers lifeline and Trojan have partnered with in China are two of the finest drop-in battery manufacturers there are, these are, not elcheapo’s. In the end this is good for the market! Xantrex also now has a battery. Xantrex is no slouch as their parent company is Schneider Electric..

Victron is Also in the Drop-in Market

LFP WARRANTIES ARE Nothing more than lawyer Speak!!

LiFePo4 Marketing:

“Each XXXXX brand Battery is Protected from over-heating, over charging…”

Warranty exclusion reality:

CONSIDER YOURSELF CONFUSED!!

Exclusion: “Damage due to over-charging”

vs. the Marketing ; 

“Each XXXXX brand Battery is Protected from over-heating, over charging…”If you’re wondering how a battery that has a BMS that “protects from over-charging Can be “over-charged” it is pretty simple.”OVER CHARGING CAN BE FROM “OVER ABSORBING”! Lead acid chargers are notorious for over-absorbing !

Of the price-point drop-in batteries, Battleborn is quasi putting their money where their mouth is. They back the battery with a 10 year “manufacturing defect” warranty. (KiloVault is 7.5 years) Please understand that Battleborn is not a 10 year warranty that covers any sort of cycle life. This warranty only covers manufacturing defects. We see it repeated over and over that Battleborn(10 year) or Dakota(11 year) have the best warranty in the industry but that warranty only covers a defect in manufacturing! Defects in manufacturing typically show up pretty quickly. Lithionics for example actually puts a cycle-life warranty on their batteries(currently the only manufacturer we know of that does this-Let us know if you find others).

That said, kudo’s to Battleborn,Dakota, KiloVault and others who put a decent “manufacturing defects” warranty on their batteries. The internal build quality of the Battleborn, is  decent compared to many batteries at this price level,but the Kilovault we believe is better and is less money. We have/cut open a slew of Chinese LFP imports and what’s inside can be HORRIFYING! The only reasonably priced non USA assembled battery we have cut into that we find to be extremely well built are the KiloVault batteries.

Will Your Manufacturer even be around to honor a 5+ year warranty?

The two brands below no longer exist…..

Have you done enough research on a manufacturer?

Could this be a reason why one of the brands from above disappeared?

WHAT ABOUT FLOAT CHARGING & STORAGE?

Float Charging

Float charging is a relic that’s left over from lead acid battery charging. Lead acid batteries directly benefit from being held at 100% SoC. LFP do not benefit from this.. Float charging is not necessary for lithium iron phosphate batteries. The only reason any lithium ion phosphate battery manufacturer even suggest a float voltage is to satisfy end users who want to continue  using legacy/antiquated lead-acid charging equipment . In no way does float charging benefit your LFP batteries. The act of holding LFP batteries at or near 100% SOC can only serve to slowly harm them and eat away at cycle-life. An LFP cell can achieve 100% SOC at just a bit over 3.4 VPC (13.6Vpack  voltage) if you’re battery manufacture suggests anything over 13.6V for float you may want to reconsider that and set it below 13.6V .You can always set it lower but should not go higher.

There are charger manufacturers out there who actually understand charging LFP batteries.Victron  is about the best known. Victron has a specific setting in their custom menu that allows you to set a “storage” voltage this is a voltage the charger drops to after a short float has been done. It can be custom programmed to allow the batteries to self discharge down to about 50% SoC before the charger kicks back in and maintains the “storage voltage.”the only chargers or inverter/chargers we currently recommend for lithium iron phosphate batteries are Victron.

Don’t take my word for it, here is Battleborn….

What About Storage?

As mentioned above lithium ion phosphate batteries do not prefer to be sitting at or near 100% state of charge for long periods of time. This is why you will see, from nearly every single legitimate drop-in battery manufacturer, a recommendation for storing the batteries at or near 50% state of charge or less

Below are snapshots from lithium ion phosphate drop-in battery manuals or specification sheets .

What about “Hybrid ” Systems (Lead & LFP in parallel)?

In one word NO!Sure you can find someone on YouTube to tell you what you want to hear, but this is not always what you should hear…

Reader Challenge:The First reader to bring us (in writing) a US based LiFePo4 Manufacturer/reseller that allows you to place lead and LiFePo4 in Parallel wins $25.00!!Here is where the Eoropean IzSO standards land

ISO/TS 23625

Even Direct from China  Manufacturers disallow it.

From LFP Manuals/spec Sheets

What About Over-Current Protection?

Lithium iron phosphate batteries can throw a ton of current into a dead short but the fuse protecting the wire must have a suitable AIC rating. AIC stands for amperage interrupt current. AIC is different than the fuses trip rating. AIC is the maximum safe-current the fuse or breaker can trip under without having an unsafe-failure. For example if a battery has too much amperage, in a dead short ,Circuit breakers can actually weld-shut before they can trip. This is why AIC matters. The bottom line is that class T fuses are what should typically be used when protecting lithium iron phosphate batteries.

ABYC TE-13

The UL image below depicts a drop-in battery with a FET BMS that is “short circuit protected”. As can be seen this single drop-in battery can stilldeliver over 5500A into a dead short! Now imagine if you have two or three of these batteries in parallel or four+. The short circuit current of a FET BMS is always considerably higher than one would assume it is When in doubt use Class T fuses for LFP.

The reason I’m showing an image of the mega or AMG fuse below is because of the growing popularity of the Victron Lynx distribution systems. These are excellent systems, we love them,however, caution must be used when connecting them directly to a battery bank. In North America over-current protection  needs to  follow the ABYC’s AIC guidance. Mega/AMG fuses are fine so long as they are downstream of A fuse or breaker that is properly AIC rated to handle the batteries short-circuit current. In other words, MEGA/AMG fuses should not be used to directly connect to a lithium iron phosphate as the primary over-current protection as the can only interrupt up to 2000A safely..

Below are the specifications for a blue Sea systems Cass T fuse. Notice the fully encased metal body and the 20,000 A interrupt capacity. Also note that these fuses are rated at 20,000A at 125 V. Tthe higher the voltage the tougher it is to meet in AIC rating. Compare this to a typical ANL fuse which only has a 6000 amp AIC rating at 32V. a class T fuse would have a significantly higher AIC rating@12 V if it was tested at this point because it meets 20,000 AIC it 125 V there was no sense in spending the money to tested at a lower voltage.

I would be sloppy if I failed to mention that any installed fuse should not be sized to carry more than 80% of its rating. This also goes for circuit breakers. This is especially true when installing inverters & charge equipment and especially alternators. For alternators a fuse of at least 140% of the alternators rating should be used. Thankfully , Blue Sea Systems is finally addressing this and putting it in their literature.

In summary, do your homework, purchase carefully, avoid direct from China imports when you can,install your system safely, use good quality charge equipment and you will be happy for many, many years and thousands of cycles.

Good luck and happy boating!

Originally Published 2014

Cutlass Bearing Removal

Every now and then a boats propeller shafting need to be replaced. A replacement can be necessary due to corrosion, bending, wear at the stuffing box, wear a the cutlass bearing or a poorly installed/machined shaft to begin with.

When choosing a shop to do this work you will need to ask specific questions to ensure you are not getting a subpar job. Many, many shops are more than eager to charge you a huge sum of money only to deliver shoddy work that won’t comply with ABYC P-06. Today, shafting work should only be done using high grade alloys such as:

Minimum Grade:
Aqualoy 17 or Aquamet 17

Mid Grade:
Aqualoy 19 or Aquamet 19

Recommended:
Aqualoy 22 or Aquamet 22

Top of the Line: (typically for high power vessels)
Aqualoy 22HS (High Strength)

Choose your shafting shop carefully!

Getting the Shaft Out

On many boats, especially sailboats,  removal of the cutlass bearing can help you avoid dropping or removing the rudder.  Dropping a rudder is a job easier said than done on many boats. On this vessel, an Ericson 34, the shaft just barely slid by the rudder once the cutlass bearing had been removed. Pressing out the coupling saved many hours of labor time, in not having to drop the rudder to remove the shaft. Of course the shaft for this article was not-reusable due to wear, so we just opted to cut it out.

To remove Cutlass bearings Compass Marine Inc. often uses our Strut-Pro tool. These tools are not perfect and cannot always press out a bearing but the success rate is high enough that the tool pays for itself in just one use.

Before the nitpickers come out in full force, the word “Cutless®” is a trademarked brand name of Duramax Marine. I therefore use the alternative accepted generic spelling of “cutlass”, just like Vetus Marine does. This is so as not to infringe on a trademarked “brand name”.

From the Duramax Marine web site: “Cutless® is a registered trademark of Duramax Marine® LLC.”

Cut The Old Shaft Out

If you know the shaft needs to come out, why risk damage to the gear box or gear box flange by trying to press the coupling off the shaft. It’s far easier and far less time consuming to simply cut the shaft out. Cutting this 1″ shaft took all of about 45 seconds to free the it from the flange and we did not risk any damage to the gear box flange in doing so. This article has more detail on removing a coupling as well as all the precautions:  Installing a PSS Shaft Seal

Slide-Hammers = NO!

Before you engage a boat yard to do this job, I will type this so it hopefully makes sense; NEVER use a “slide-hammer” to remove a shaft from a coupling if the coupling is attached to the gear box!

If you want to throw 3k out the window feel free to use a slide-hammer, if not, use safe and proper procedures for removing the shaft from the coupling such as a coupling press tool like the one from Buck Algonquin pictured below.

Yards that don’t care about your boat or gear box, use slide-hammers to remove prop shafts from the couplings even when the coupling is attached to the gear box. Yes, it’s quick & dirty, and the damage to your gear box can largely goes unseen, for a period of time, but DO NOT be fooled by boat yards with slide-hammers and do not allow a yard to use one on your boat.

Let me phrase this another way. Would you go to a dentist who used a Milwuakee Sawzall to remove a tooth?? No, of course not. To those in the know, a dentist with a Sawzall is the same level of ignorance as a slide-hammer. A slide-hammer is the wrong tool for the job. I know many tech-schools blindly teach this, and they are grossly wrong, but you now have the ammunition, and are a better educated boater. It’s your boat, so just say no to slide-hammers!

What’s so wrong about using a slide-hammer?

A slide-hammer is essentially a long piece of metal pipe that threads onto your shaft where the prop nuts go. It’s about 4 feet long and has a heavy metal weight on it. The weight is slid up the bar, towards the prop shaft nuts, and then thrown or “slid” down the bar until it hits the end and SLAMS to a sudden & abrupt stop. The concept is that it breaks the coupling from the shaft when the weight comes to the sudden and abrupt stop. This tool does what it does very well, but that is not the end of the story. The reality is that a slide hammer destroys gear boxes and brinnels the bearings in the process.

The Damage Done is not Always Obvious

The worst part about slide-hammers is this destruction of your gear is not always readily apparent. Because of this boat yards and their workers assume they get away with it and it “works”. Yes, it works, it works to destroy gear boxes. If your boat yard tells you “we do it all the time” please do yourself a favor and find a new yard.

Slide hammers can cause brinneling of the bearings or races in the gear box. The shock loads imparted on the static bearings, by the “slide-hammer”, actually create flat-spots in the races or bearings themselves. Your gear box may appear to work for some time after the slide-hammer event but eventually, the damage rears its ugly head and it’s next to impossible to lay blame on the slide-hammer user as they rarely fail instantaneously.

About twelve years ago I was at a yard when I overheard the yard-boys slamming & slamming & slamming a slide hammer to free a shaft from a coupling. All of a sudden I heard one last SLAM, then a CLUNK and the sounds of metal bits on fiberglass, then “OH $HIT!”…… You guessed it they hit it so hard they blew the case of the gear box apart and destroyed it. They literally cracked the iron gear box wide open. The shaft, after all the beating that finally destroyed the gear box, was still firmly embedded in the coupling.

Caveat emptor on slide-hammers..

Double Taper Shaft

While many marine shafts, such as those used on many sailboats and small trawlers are a straight shaft at the coupling end, others may be considered a “double taper” meaning the coupling end is tapered just like the propeller end.

As can be seen above, this shaft is a double taper on both ends. Many sailboats however lack the space for a double taper coupling, because double taper couplings are typically longer. Sailboats typically use a “straight coupling”.

The point of this image is to make darn sure you know what type of coupling you’re working on before trying to remove it…

A New Split-Coupling

For tight spaces, like this Ericson 34, Buck Algonquin makes a great split coupling. I typically prefer a straight split-coupling to a straight solid coupling but, both work if properly installed fitted and faced. It is these small nuances of a correct prop shafting job, such as fitting & facing, spotting, chamfering corners etc. that matter most what selecting a shafting shop to do your work.

The nice thing about this split-coupling is that it’s no longer than a standard solid coupling and is actually a touch shorter than most. The “S” designates “short”.

This is the new split coupling from the box above. You can see how compact it is on its overall length. If you have a tight fit one of these may be a good choice.

Fitting the Coupling to the Shaft

The two shims are placed in the “splits” to make the bore ID the same at both ends before “fitting” begins.

I hear it repeated all over the internet boating groups & forums that a split coupling is intended for DIY installations. While it certainly can be installed by a DIY, without a machine shop, it will not be a “correct” fit unless it has been properly fitted & faced to the shaft. Most DIY’s do not own the tools for this type of work.

In this image the coupling is being prepped for “fitting” it to the shaft. In order to do this, the split end of the coupling is shimmed parallel while the coupling is very carefully honed for a light interference fit. “Light interference fit just means the coupling actually requires some force to get the shaft into it. This “fitting” of the coupling to the shaft is just as critical with a split coupling as it is with a straight coupling.

A split or solid coupling that  “slides” onto the shaft = incorrect fit and can be dangerous!

These couplings purposely ship a tad undersized for the SAE shaft tolerances. This allows a competent shafting shop to “fit” the shaft to the coupling. The proper fit for a straight coupling is a light press fit or light interference fit. This means it does not just “slide on” and requires some light tapping, or heat to expand the coupling while it is installed over the shaft.. Getting this level of fit can be time consuming.

Inside Finish, Before Fitting

The inside of the coupling is reamed, then honed to get the final fit.

Rough Reaming Tool

This is the rough reaming tool. The finishing is done with grinding compound or other means of honing the coupling bore.

Flange Is Bored To Fit The Shaft

With the flange held tight in the jaw of the lathe, the reamer is very carefully adjusted and rotated to remove just barely enough material to start to get closer to  a perfect fit. The final fit is done by hand with valve-grinding compound. It takes some time, and a lot of experience, to make it fit just right. This one took about 25 minutes until the fit was just right.

Should Be A Light Press Fit

Here, the machinist is test-fitting the coupling to the shaft. A soft lead mallet is used to gently tap it on. This is not pounding but rather a light “tap fit”. Just enough interference so it won’t go on by hand is how it is done. With a good fit you may need to heat the coupling to make the shaft slide into it when doing the install at the boat.

Shafting Material is Cut To Length

For the shafting on sailboats & most power boats we only specify Aqualoy 22 or Aqualoy 22HS. This shafting is a high-alloy austenitic stainless steel that offers tremendous corrosion resistance and excellent strength properties. It is some of the best shafting there is and is made by world renowned Western Branch Metals.

Here a length of 1″ Aqualoy 22 is cut to length for machining.

Checking Shaft Run Out

Once the shaft is cut to length, it is then tested for run out. A good shafting shop should always do this, even with a brand new shaft. If it does not meet tolerance it needs to be made true. This was was out by less than .001″ for a 52″ shaft. This shaft was also checked for true after the machining process.

Machine for Cutting the Shaft Taper

Once the shaft is cut to length it’s placed in this very expensive machine to cut the taper, or tapers, if it’s a double-taper shaft.

Keyway Cutting Machine

This is the machine used for cutting the coupling and propeller end key ways.

Spotting The Shaft

After the coupling has been fit to the shaft, the set screw hole needs to be “spotted” into the shaft. This like many of the other nuances is a requirement under ABYC P-06. The drill press is spotting the shaft in this picture.

Spotting is the creation of a small dimple in the shaft for the head of the set screw to recess into. If your shaft is not spotted for the set screw/screws you have a poorly machined shaft that does not meet the ABYC marine safety standards. Some unscrupulous vendors do cut this corner.

No Spotting

The above image is a prime example of sloppy machining. This shaft literally fell out of the coupling after a DIY pressed it off and tried to re-use it. The layer of rust that broke free was the fit”. The boat took on enough water so that is was a complete loss and the owner carried “liability only”. He’d spent over $10K on the boat since purchase and it was all gone in an instant because he did not follow best practices. Best practice when a coupling is removed is to drop it at a shafting shop for a “fit check”.  In most instances a removed coupling will need to be replaced. This coupling was clearly never “fit” correctly to the shaft to begin with and then the set screws were never spotted to act as a fail-safe back up. Don’t let this happen to you. Insist on a light interference fit and properly spotted set screws!

Do Not Re-Use a Used Coupling Without a Fit-Check or Fit & Face

This DIY had actually taken the time to read this article. Sadly for him, he chose to ignore the advice on properly fitting couplings. You guessed it, he re-used the old one when he installed a new PSS Seal. He penny-pinched this in order to save approximately $80.00. In the end it cost many thousands in repairs and an insurance claim that wound up getting him cancelled the next year. His insurance premium is now more than double what it had been, every year.  Lets see, spend $80.00 now or $26,000.00 a few weeks later? I call that penny-wise, pound foolish.

Tow to Boat Yard $$$

Haul Out – $$$$

Short Term Storage -$$$$

Labor to Drop Rudder -$$$$

New Shaft & Coupling – $$$$

Prop Repair (prop hit hull & rudder) – $$$

Strut Repair – $$$$

Water Damage Repairs – $$$$$$$ (boat was sinking when shaft backed out)

Rudder Repair $$$ – (prop hit rudder when it backed out of the boat)

Transmission Repair – $$$$

Losing of 85% of the Boating Season = Priceless

Please let the seriousness of cutting corners, when removing a coupling, sink in!

A Spotted Shaft

A shaft made by a reputable shafting shop will have spotting that looks like this;

Facing the Coupling to the Shaft

With all the other work done the coupling is finally installed and torqued properly to the shaft just as it would be on the vessel. The shaft is then spun in the lathe and the face of the coupling is made true to the shaft. This image shows the coupling before the facing has occurred.

Fully Fitted & Faced

Just like a brake rotor lathe the face of the coupling is made to rotate perfectly with the shafting. If you receive a shaft and rotor from a prop-shop and the face does not look “freshly cut” please do yourself a favor and question this. It would be extremely rare that a new shaft and coupling did not require an facing.

Now that you know what to look for you can now be your own best advocate when choosing the right prop shafting shop/supplier..

Good luck and happy boating.

The 1/BOTH/2/OFF Switch

Preface: I’ve seen & read many on the internet suggest that “The 1/2/BOTH is RC/Rod’s/Compass Marine’s preferred switching method”.. Let me be clear on this point; this is not our preferred method, it is simply a method.  This article is only intended to showcase how the 1/2/BOTH switch can be used in an easier and often less confusing manner. Many boat owners don’t have the luxury of starting from scratch and the existing switch can usually be re-used/re-purposed easier, and in a less costly way, than converting to an entirely new switch configuration..

Basic Design Principles for Battery Switching:

1- Bank Isolation – The ability to isolate a battery bank from both loads and charge sources in the event of a bank or battery failure.

2- Cross-Connection Use – The ability to use either on-board battery bank as the sole use bank, meaning it serves as starting and house load bank in an emergency, This design criteria should always include #1.

3- Ease of Use – A battery switching design is no good if the boat owner does not understand it.

One area of confusion we see fairly routinely is a boat-owner misidentifying the 1/2/B switches terminals. A 1/2/B switch has just three terminals and four positions.

Terminals:
Bank 1 – Input stud 1 in photo
Bank 2 – Input stud 2 in photo
“C” Post – Output stud in photo

“But RC where does DC ground connect to on the 1/2/B?”

If I had a dime for every-time this question was asked, I’d not be writing this article. The 1/2/B is switching only the DC positive conductors and has nothing at all to do with DC negative. Please DO NOT connect DC neg to a 1/2/B switch!!

Terminology Used In This Article:

1/2/B – A battery switch that has position 1, 2 OFF and a paralleling feature often called BOTH, COMBINE, ALL or 1+2
C Post – The “C” Post is the COMMON post which is also referred to as FEEDER, COMMON or OUTPUT
Both – When the switch is set to 1+2, BOTH, COMBINE or the ALL position both battery banks are now physically wired in PARALLEL

The 1/2/B Switch is a Very Common Factory Wiring Configuration:

Over the years most all boat builders, of both sail and power, have installed the simple and redundant 1/2/B switch. The switch, I believe, has gotten an undeserved bad rap over the years. Why? It’s really not necessarily due to the switch itself, but rather due to the way most builders install them, and the way many boat-owners have used them.

Despite the bum rap, the 1/2/B switch remains a versatile & redundant single-switch battery selector. Surprisingly, even today, they are still the #1 selling multi-bank switch. The 1/2/B offers more redundancy and isolation than just about any other easy to use configuration. The “easy to use” part is arguably debatable. It should be easy but lack of a complete understanding leaves many boaters confused.

1/2/B Switch Confusion Issues Can Result In:

• Unnecessary Switching & Forgetfulness
• Two Dead Battery Banks at the Same Time
• Damaging Voltage Transients
• Forgetting to Charge a Bank

Confusing Lingo:

START & HOUSE Banks – Like anything in the marine market the 1/2/B can develop it’s own levels of myth & lore. One of the most common misconceptions is that you have a Start Bank and House Bank. Sure, you can assign a switch position to HOUSE and START but they are really EVERYTHING banks. A “START” battery, by definition, is really dedicated to only starting an engine, no house loads.

If you wish to continually move the switch from 1 to 2 then 2 back to 1 etc. etc. it may feel like you have a START & HOUSE bank but you really don’t. In the #1 or #2 position each bank serves both starting and house purposes. Starting and House services cannot be isolated from one another with a 1/2/B unless you add another ON/OFF switch. It is for this reason that we refer to the banks, with a 1/2/B as HOUSE and START/RESERVE. This is still actually incorrect terminology, but a bit more accurate. As you read on you see more of what we mean by this. Technically, and accurately speaking, you have Bank 1 & 2 and each of those positions do both house and starting duties simultaneously.

Builder Blunders?

The 1/2/B switch, as wired by most builders, becomes a Bank Selection and Charge Directing switch. This means what ever position you have the switch set to, is where your on-board energy comes from, and where the engines alternator sends its charge current.

What Bank Selection and Charge Directing Mean:

1/2/B Switch Set To;

Bank 1 = DC loads are drawn from bank #1 and alternator charging goes to bank #1
Bank 2 = DC loads are drawn from bank #2 and alternator charging goes to bank #2
BOTH = DC loads are drawn from BOTH banks and alternator charging goes to BOTH banks
OFF = Both battery banks are isolated/OFF

Note: Even when set to OFF a bilge pump, propane sniffer, stereo memory or VHF may still be direct wired to the house bank so the vessel may still have live 12V wires..

Typical Factory Wiring:

Most boat builders simply wire the alternator circuit back through the starter feed wire to the “C” or common post of the battery switch. The “C” post is energized when you flip to 1, 2 or BOTH and is isolated or disconnected when you switch to OFF. This wiring method is cheap & easy for the boat builder, but leaves owners with lots of room for human error and misunderstandings.

The factory wiring works simply, and allows you to choose which bank you are charging or drawing from by selecting that bank, or both, on the switches face-plate. In the drawings below, the green lines are showing the 1/2B switch connecting the alternator, starter motor and the  DC panel loads, to the bank or banks selected, via the “C” post of the battery switch. You can visually see the path the alternator takes to get back to the battery bank. The green lines represents the switch position.

Set it to bank #1 and bank #1 gets charged/discharged. (Follow the green line)

Set it to bank #2 and bank #2 gets charged/discharged.

Set it to BOTH and both banks get charged/discharged.

Mishaps and Human Error:

Mishaps and human error creep in when an owner forgets to manually switch & charge bank #2 and now bank #2 never gets charged.  Far too often an owner will leave it on BOTH, and then run both the banks completely dead. If this happens, and it does, you’re $hit out o-luck…. We call this the Human Error Factor or HEF.

Owner Blunders?

So why may the factory wiring method be a poor choice? It’s not necessarily poor choice, if you understand your system and how to use it.

Human Error Blunders;

Blown Alternator Diodes & Voltage Transients:

This big blunder happens when you, or a crew mate, tries to switch to another bank and pass the battery switch through the *OFF position, even momentarily. With the engine running and the alternator charging this creates an open-circuit between the alternator and the load (load = battery bank) it’s charging. Momentarily passing through OFF, or disconnecting the load from the alternator, can cause a massive voltage spike as the load/ battery bank is disconnected from an alternator. This quite often results in damaging the alternators rectifier diodes & rendering it non-operational near instantly. it can also damage sensitive electronics that are connected to the “C” post of the switch.

*Most quality 1/2/B battery switches, from reputable manufacturers like Blue Sea Systems, BEP/Marinco, Guest & Perko, are designed to be make-before-break. Make-before-break means that as you turn the switch from position 1, to BOTH or 2, the previous position does not open-circuit or disconnect until the next position can carry the current.

As some battery switches age they can wear and become break-before-make. For this reason it is not a good idea to move the switch while the engine is running unless you perform an occasional make-before-break test. The best way to test your switch is to turn on the cabin lighting (incandescent bulbs work best not LED’s) then slowly rotate the switch from 1 to BOTH to 2. If the incandescent light/s flicker at all during this rotation, replace the switch. Even a fraction of a second disconnect is enough to cause an alternator load-dump.

The Load Dump:

Picture, if you will, a Top Fuel Dragster. The drag car is moving at 200 MPH when it smashes directly into a 10′ thick solid concrete wall. All that energy/mass, and no where to go, means instant destruction. The concrete wall is akin to what happens in your alternator when you shut the battery switch off during charging, especially high-current bulk charging. This open-circuit event, between the battery and alternator, acts as the concrete wall and all that energy has nowhere to go. The result with an alternator is that this energy has to go somewhere, so it skyrockets the voltage instantaneously. The result of an open-circuited battery switch is called a load-dump. A load-dump creates a very fast voltage spike/transient that can destroy the rectifier diodes. Here at Compass Marine Inc., we repair quite a few alternators each year due to battery switch load-dump blunders.

Ever wonder why a 1/2/B switch has this warning? Well, now you do…

Damage to Sensitive Electronics:

Unfortunately it’s not just alternator diodes we need to be concerned with, in a battery switch disconnect / load-dump. A lack of charging is what most owners notice first, but the damage may not end there. If you take a look at where your DC loads are connected, this just happens to be the same exact place as the factory wired alternator, the c-post. When the switch is accidentally opened, while charging,  the alternator is instantly disconnected from the battery and all that energy has to go somewhere. Where does it go? Follow the diagram below and you’ll see.

The voltage transient/spike that’s created by accidentally opening the battery switch, while charging,  goes straight into your sensitive DC electronics because the alternator and DC panel are connected to the same c-post stud, which is no longer connected to the battery/load.  The voltage transient from a battery switch disconnect often destroys the alternator diodes and it can also damage or murder your sensitive DC electronics. It’s not uncommon for us to find multiple other items damaged when a customer comes to us for a bad alternator, and the diagnosis is blown rectifier diodes.

In theory, the voltage regulator would react and stop this voltage transient, after all they do limit voltage, but the spike happens far too fast for the voltage regulator to react. This damaging transient occurs in microseconds. As you now know, when you open the battery switch, while charging, there is a high likelihood the diodes in the alternator will be blown. A mistake like this can leave you with no alternator and potentially ruined navigation electronics too. Sadly the factory wiring does nothing to limit or protect against this. Some newer alternators, on late model engines, utilize avalanche-diodes. Avalanche diodes are more durable and designed to limit the voltage transient, but most existing marine alternators do not utilize avalanche diodes..

Alternator Field Disconnect:

Some battery switches even feature an Alternator Field Disconnect or AFD feature. The AFD consists of two terminals that break the alternator field or external regulators power wire slightly ahead of the 1/2/B’s OFF position opening. Unfortunately, most vessels with see with AFD switches are either not using it or the AFD circuit is wired incorrectly. If you don’t have access to the field wire, inside the alternator, the AFD feature does you no good.

We’ve even seen alternators where the factory alternators key-on excite-wire was passed through the AFD circuit yet the diodes were still blown. Why? The excite wire is only needed to get the alternator started. Once the alternator is spinning, and producing power, cutting +12V to the excite-wire does not always de-power the regulator, and the alternator keeps on chugging away.

Alternator Protection From Load-Dumps:

If you wish to keep your 1/2/B factory wiring, and you understand the nuances, it would be a very wise idea to install a Sterling Power Alternator Protection Device. The Sterling APD is designed and intended to clamp or limit a voltage spike/transient to a safe level and protect both the alternator and other DC components.

Here the Sterling Alternator Protection Device is shown with a LiFePO4 drop-In battery. Drop-In LiFePo4 batteries have internal BMS switch (battery management system switch) that can essentially do the same exact thing as flipping a 1/2/B switch through the OFF position. Installation is as simple as two wires and a fuse, and it’s inexpensive insurance.

The “I Must Set it to BOTH to Start the Motor” Mind Set:

Sometimes blunders are just caused by a cascade effect. The “I Must Set it to BOTH to Start the Motor” is typically flawed and unnecessary. At the same time, it’s a reality in some owners minds because the BOTH position acts as a Band-Aid for weak batteries or a poorly wired system.

In the case of starting a motor, the BOTH position is typically hiding or covering up other issues and does not actually solve the issue at hand. On the flip side, it leads to a cascading effect where forgetfulness can lead to error. The “You must use BOTH to start.” mantra has actually climbed to urban-myth status level.

You Should Not Need to Use BOTH to Start Your Motor!

If you need BOTH banks to start your motor, you have other issues such as:

• Failing Batteries
• Batteries Not Sufficiently Sized to Start Your Engine
• Bad or High Resistance Terminations in Your Battery Wiring
• Undersized Starter Motor Wire
• Failing Battery Switch
• Dirty or Corroded Terminals
• Faulty Starter Motor
• Wiring issues in the starter solenoid circuit

In most cases your engine can easily be cranked by the house bank. Keep It Simple..

“But RC engine cranking uses lots of battery capacity, isn’t this bad for a house bank?”

Lets examine the actual math on this one to hopefully explain the misnomers surrounding engine cranking. Compass Marine Inc. has invested in the expensive tools that can measure engine cranking performance with high precision. The average cranking duration’s we measure, as defined by a loaded to un-loaded starter motor, is 0.65 to 1.5 seconds. The math & images below are from starting a 44HP diesel motor at 32F with a deep-cycle house bank. Most boaters will never start a marine diesel at 32F.

The math on how much energy is actually consumed from cranking is pretty straight forward:

0.75 Seconds is approx 0.002 hours – 286A X 0.0002 = 0.06 Ah

1 second is approx 0.0003 hours – 286A X 0.0003 = 0.086 Ah

2 Seconds is approx 0.0005 hours – 286A X 0.0005 = 0.14 Ah

3 Seconds is approx 0.0008 hours – 286A X 0.0008 = 0.23 Ah

4 Seconds is approx 0.001 hours – 286A X 0.001 = 0.28 Ah

5 Seconds is approx 0.0014 hours – 286A X 0.0014 = 0.40 Ah

We’re not just shooting from the hip on these numbers. The images below show the entire story..

Resting Bank Voltage > Tested CCA of The Bank > Rated CCA of Each Battery > Battery Case Temp

As can be seen above, when we parallel deep-cycle batteries rated at only 675 CCA, we wind up with 2071 CCA for cranking at 0F (these batteries were preforming slightly better than 675 CCA). This screen translates the 32F temp to a 0F CCA rating. When the batteries are warm the cranking capability is much greater.

Cranking Current Graph for Entire Duration of Starting Event

In the image above we can see how this very cold 44HP engine drew slightly over 640A for the in-rush, but the cranking amperage declines rapidly after the initial in-rush.

Averaged Voltage, Averaged Cranking Current, Duration of Start  (Loaded to Unloaded), Circuit Resistance

The screen shot above summarizes the averages. Despite a 640A+ peak in-rush the averaged cranking current, from loaded to unloaded starter motor, was just 286A and the total cranking duration was just 0.765 seconds or 765 mS. For what it is worth, this particular bank is protected by a 300A fuse and has done well in excess of 1200 starts, over a 12 year period, and never once nuisance tripped the fuse. Why? Because the duration of a starting event is very short, this one 3/4 of a second, and this does not even come close to the trip-delay curve of the fuse.

Engine Cranking Reality:

There is little dire need on most smaller boats, especially ones with small aux diesels (sub 150 HP) or gas engines, to require a *dedicated starting battery.

*Dedicated Starting Battery – A hard wired battery bank used only for starting purposes and nothing else, unless for emergency situations. A dedicated starting battery is connected directly to the starter motor when the start battery switch is on.

A dedicated starting battery is always nice, but it usually means a new switch and wiring reconfiguration to do it correctly. With many battery switches located in DC panels, & these are usually not ABYC compliant, this is often not an easy undertaking. By tweaking the existing 1/2/B, & how you use it, you can make the system more fool proof and easier to use.

A large chunk of our customers boats have started engines, for years, on their house banks, we’ve now seen the math as to why this is so and why this works. We even have commercial fishing boats starting large Cummins, Cat and John Deere engines with 6V Golf Car batteries.

How? To grasp this we need to understand that a house bank is typically much, much larger than a start bank. Because of this, and even when the batteries are deep-cycle, the house bank almost always has more cranking capacity than the single, & typically small, starting battery.  When we parallel batteries, in a house bank, we the cranking capacity is additive. For example, three 100Ah 600 CCA deep-cycle batteries quickly become 1800CCA when wired in parallel.

For owners that understand how to use a 1/2/B, in a more simple manner, this means they only use position #1 (HOUSE) and OFF. The only time to do anything different is when there is an emergency or to occasionally test the reserve-bank to ensure it is still performing well. The 1/2/B works really well as a USE SWITCH, but it can be tweaked to be better.

“But RC the guy down the dock says deep-cycle batteries cannot be used for cranking.”

Sadly, your dock-expert is misleading you on this. I will let Trojan Battery sum this one up.

The key here is “a deep-cycle battery“, meaning single battery, and when most all house banks on boats over 25 feet these days are using multiple deep-cycle batteries you now have many more cranking amps in the house bank than you do in your typical starting battery. Even at 50% DoD a typical house bank will still have more cranking capability than a single starting battery. Unless you have massive diesel engines, or a very small single battery house bank, keep it simple and just crank off the house bank. You can now delegate bank #2 as a reserve/emergency bank.

The Cascading HEF : “I Forgot to Switch From BOTH Back to HOUSE“

The use of BOTH to start you motor, or when charge directing, requires that you remember move the switch off of the BOTH position when you shut the motor off, or shortly after. Unless you need to be in BOTH for charge directing, there should be no other need for this position, in a well operating system, that’s also properly wired. As discussed above, unnecessary switching can lead to potentially blown alternator diodes, damaged electronics or two dead banks as opposed to just one. Using the BOTH position to start the motor is indeed unnecessary switching that can lead to human error issues.

An expensive scenario is that happens all too often, is when an owner has forgotten to switch off of BOTH and killed both banks. Doing this leaves no second / reserve battery to start the motor with. You’d be surprised how many calls we get each year for this exact issue.

Don’t Blame the Switch:

The normal human tendency, when these blunders or HEF happens, is to blame the “stupid” 1/2/B switch. The 1/2/B switch is like a gun, the gun did not pull the trigger, the owner of the gun did. How is the switch “stupid”? It’s not, but the owner may be. How is the switch “stupid” when the owner makes a mistake? It’s not, it did exactly as it was set & wired to do, but the 1/2/B is still often blamed for owner ineptitude.. This is the bad rap we referenced earlier.

Let’s Make the 1/2/B Easier & More Fool Proof

The 1/2/B as a USE SWITCH:

Converting a 1/2/B to a  USE SWITCH is actually quite easy and minimally cost invasive. Once you do this it becomes a SIMPLE ON/OFF scenario. That’s it, ON & OFF, or more accurately #1 & OFF. Once converted to a use switch it is no longer a charge directing switch, or a start on BOTH or #2 then remember to move to #1 switch. It is basically an ON/OFF switch.. Simple, effective and you likely already have one if you’re reading this.

Wiring Upgrades:

The 1/2/B switch is a very useful device and there are a few small changes you can do that can make it even more fool proof. Most of what you need for a very simple and redundant system is already there, so there is little need to spend more money on new switches or drill yet more holes in your boat over what you likely already have. This is of course predicated on the fact that you are comfortable with the idea of not using a dedicated starting battery.

Below Are Illustrating 1/2/B Switch Upgrades in Multiple Levels:

Level 1 Upgrade: In the image below we have the Level 1 Use Switch Upgrade. It consists of adding a Charge Management Device, in the case of this article we have chosen to illustrate the Blue Sea Systems ACR. Once installed the ACR will provide for fully automated charging of both banks. The addition of the ACR eliminates the need to move the switch for charge directing. We’ve also added some fuses, which are required under ABYC standards. Please read our article on Automatic Combining Relays for a better idea of how they work.

You don’t have to use an ACR and the class of “Charge Management Devices is now quite vast. You could also use an:

• Balmar Digital Duo Charger
• Xantrex Echo Charger
• Sterling Power ProBatt Ultra DC to DC Charger
• Victron Orion TR Smart DC to DC Charger

The ACR just represents an excellent low cost option.

Making Sense of Automatic Charging Relays (LINK)

Any bank that can be called upon to start a motor, and with a 1/2/B that is either bank, should ideally have a fuse capable of doing so without nuisance tripping. The bare minimum fuse size, for small diesels, would be 250A but preferably 300A as the minimum. The start bank can also be fused on smaller diesels, but it’s not technically a requirement, under the ABYC standards, to fuse the cranking circuit.

Level 2 Upgrade: In level 1 we reduced the need for unnecessary switching for charge direction by adding a Blue Sea ACR. Unfortunately level 1 leaves open the possibility of a load-dump. The Level 2 upgrade adds a Sterling Power Alternator Protection device to protect against a 1/2/B induced load dump. The alternator is still wired in the factory configuration and we only add an ACR and Alternator Protection Device. You can now get on the boat set the switch to Bank #1 and use the boat. When you’re done flip the switch to OFF. No need for unnecessary switching and human error induced blunders are drastically reduced..

Level 3 Upgrade: The level 3 upgrade wires the alternator directly to the house bank with proper fusing rated at 150% of the alternators rated output and within 7″ of the house banks positive terminal. This upgrade offers optimal charging performance when an owner has an alternator with an external regulator. Wiring direct to the house bank means the alternator cannot be “load-dumped’ by the switch because the alternator is now directly connected to the “load” or bank.  The charging performance aspect is realized by the voltage regulator now sensing voltage closer to the bank and this improves fast charging performance. With a 1/2/B in factory wiring configuration the closest you can sense voltage for the alternator is the c-post of the switch. This typically means less than stellar charging performance. For more on this please read:

Alternators & Voltage Sensing – Why It Matters

There are numerous performance benefits for alternator charging when direct wiring the alternator to the house bank. These benefits are above and beyond the elimination of a 1/2/B switch load-dump. There are however some important nuances to the Level 3 upgrade. If you look closely you’ll notice that we’ve moved the ACR connections & alternator input to the load side of the house and start bank fuses.

The reason for this is rather simple. In the event of a bank failure, and we see them, you will want to be able to keep the alternators charging output with the good bank. This can be done simply and easily by removing the house or start bank fuse. The removal of the fuse  allows you to 100% isolate the bad bank yet keep alternator charging with the now “reserve” bank.

In the event of a house bank failure you would simply pull the fuse on the house bank and set the 1/2/B to BOTH. The alternator can now charge the start/reserve battery, and the entire vessel can run off that bank while the failure of the house bank is dealt with. An even better approach, than pulling fuses, would be to place an ON/OFF battery switch right after the house bank fuse inside the battery compartment.

What if I want to keep my 1/2/BOTH and have a dedicated start battery?

Actually this is pretty easy. In the diagram below we’ve taken the Level 3 upgrade and simply added a Blue Sea Systems ON/OFF battery switch. This design means you retain the ability to start off the house bank in an emergency as well as maintain all the safety and isolation features the 1/2/BOTH can offer.
The diagram below is one that works well when an owner  desires a dedicated starting battery but also want to retain the flexibility & isolation of the 1/2/BOTH switch.

Simply flip to #1 and ON and your ready to go. When you’re done flip both switches to OFF. Label them carefully, Blue Sea Systems sells the perfect labels.

Use Modes:

For customers with this set up I simply leave a copy of all the scenarios of switch use on-board. This is what it looks like..

NORMAL EVERYDAY USE:

ISOLATED START & HOUSE
Note: Alternator charges HOUSE and ACR charges START.
1/2/BOTH = #1
ON/OFF = ON

EMERGENCY SCENARIOS:

START & HOUSE PARALLEL
Note: This overrides the charge management device & allows more current to charge the START bank.
1/2/BOTH = ALL
ON/OFF = ON

Emergency Situ #1 – START – Provides HOUSE & START Duties:
Note: Use if the HOUSE bank were to fail. This 100% isolates the HOUSE bank & uses the START bank for everything.
ON/OFF = ON
1/2/BOTH = ALL
Remove House Bank Fuse

Emergency Situ #2 – HOUSE – Provides HOUSE & START Duties:
Note: Use if the START bank were to fail. This isolates the START bank & uses the HOUSE bank for everything.
ON/OFF = OFF
1/2/BOTH = ALL

The 1/2/BOTH with an additional ON/OFF  is certainly more complicated but more flexible than some other systems. Some battery switches such as the Blue Sea System Dual Circuit Plus force you to use the “combine” feature in an emergency, where you may be paralleling a perfectly good battery bank with one that has an internal short.

Combine as your only emergency option is absolutely not the same as the ability to 100% isolate a bad bank. This image is why you don’t want to combine a good battery to one that has failed or shorted internally. The runaway battery had already been identified and disconnected from the rest of the bank and yet it was still registering 154F.

You Have Lot’s of Options

Before you throw your hands in the air, and potentially throw out a perfectly good battery switch, consider making your 1/2/B switch a USE SWITCH. The 1/2/B as a use switch is still not our favorite switching configuration, but it is often the least expensive upgrade. The upgrades listed above are inexpensive, easy, eliminate needless switching and make the system easier to use.

The options for battery switching are almost limitless, but please always design for:

1- The ability to completely isolate a bank (paralleling with a potentially failed bank is not a suitable option)

2- The ability to use the vessels second bank, for everything, in an emergency

3- Keep it simple & easy to understand.

Good luck and happy boating!

Incorrectly Wired Service Disconnect Switch

This article is part of an on-going series on marine alternators. Our other articles can be found in the link below:

MarineHowTo.com Category – Alternators (LINK)

Terms used in this article:
Alternator B+ = Positive Alternator Output Wire
Alternator B- = Negative Alternator Output Wire
Regulator B+ = Red regulator power wire for the MC-614 (terminal #2)
Regulator B- = Black wire in regulator harness used for negative power and voltage sensing (terminal #1)
Load = Battery Bank
Full Field = Alternator regulator driving the maximum field
ASD = Alternator Service Disconnect Switch
AFD = The Alternator Field Disconnect feature found on certain battery switches

What is the purpose of a Service Disconnect Switch?

The service disconnect switch is designed to disconnect the alternator B+ wire from the battery so a service technician cannot short a wrench to the B+ stud while working on the engine. It is there to help service technicians isolate the alternator from the battery bank, that’s it.

Why would my alternator be directly wired to the battery bank?

When wiring any high performance marine alternator & regulator the optimal charging performance will be realized when wired in the following manner:

• The alternator B+ & B- are directly wired to the house bank or the bank that gets routinely discharged the most
• The alternator regulators voltage sensing circuit is directly wired to the same bank the alternator is wired to

If your paying attention to the wiring laid out above, you’ll quickly realize that even with the main battery switches set to OFF the alternator regulators B+ / power wire still has live power from the house bank. This can be dangerous to a service technician who may be working on your engine and not know or realize the alternator is direct wired to the house bank. Don’t worry, there is an easy way to handle this and it is called an Alternator Service Disconnect Switch or ASD..

Service Disconnect Switch Best Practices

1. Should be mounted near engine, in the engine bay (out of sight of your on-board guests)
2. Should be clearly labeled as an “ALTERNATOR SERVICE DISCONNECT“
3. The power for the regulator must be wired on the alternator side of the service disconnect switch!
4. Use the ASD switch only when servicing the engine

Yes, #3 is bold for a very good reason. The most critical aspect of wiring a service disconnect switch, and one that is far too often over-looked, is to ensure the external regulator cannot boot up with the alternators B+ terminal disconnected from the load or battery bank. This means placing the regultors power wire on the alternator side of the ASD switch circuit so that when the ASD is off the regulator is also off.

“Rod, Why on Earth does that matter if the alternator is disconnected, isn’t it disconnected?”

The answer to the above question simple:

Darrell the diesel guy is working on your fuel injection system and he notices that you have an alternator service disconnect switch and OFF it goes.. Darrell knows what an ASD is, because it is CLEARLY LABELED and turns it OFF, while working on the engine, so he does not weld a wrench to the manifold. When Darrell is done servicing the engine, he cleans up, closes the engine bay, but forgets to flip the ASD switch bank to the ON position. D’oh!!

A few hours later you arrive to use the boat. You fire up the engine and think; “wow this baby is really smooth“. A few minutes later you get a whiff of that acrid electrical burning smell……. Ohhhhh…..

If the alternator B+ is physically disconnected from the battery bank, but the regulator is still allowed to boot up, with no “load” on the alternator, the regulator will go to full field and voltage will shoot through the roof. The alternators rectifier diodes are only rated for so much voltage and your expensive alternator can literally have all the smoke escape from it. Not good!

Correctly Wired Service Disconnect Switch – Balmar MC-614

In this image the regulator B+ / Terminal #2 has been moved to the alternator side of the ASD switch. Even if Darrell forgets to turn it back on, the regulator cannot boot up.

An ASD is an excellent way to keep your performance alternator system safe for yourself or service technicians who may be working on the engine. It will also allow you to yield the alternator performance you’ve paid for. For the most part, perhaps 99.9% of the time, this switch left in the ON position. The only time an ASD is used is when servicing the engine. However, in that 0.1% occasion that Darrell forgets to turn it back on, you don’t want to ruin your alternator by having the regulator boot up into a no-load situation.

The Balmar MC-614 external regulator is unique in that it has a separate positive voltage sensing terminal (terminal #9). This means the regulator B+ / Terminal #2 power wire can be installed on the alternator side of the ASD, and not negatively impact charging performance. For more on voltage sensing for optimal chaging performance, please see this article:

Alternators and Voltage Sensing (LINK)

What About the Balmar ARS-5?

With a Balmar ARS-5 regulator, the regulator B+ / Terminal #2 is also your positive voltage sensing circuit and sensing the back of a switch, one that is so close to the alternator, eats away at your quick-charging performance. For a Balmar ARS-5 regulator it will be best to route regulator B+ / Terminal #2 through the AFD circuit (alternator field disconnect), of an AFD equipped battery switch, and then onto battery bank positive terminal or the always on / charge bus. The Blue Sea Systems 9004e is a simple ON/OFF switch with an AFD circuit.

The drawing above also includes an “Always On / Charge Bus”. A busbar like this is a great place to install fusing, such as busbar mounted MRBF fuses. The Always On / Charge Bus is a great place to collect all your charge devices such as alternators, chargers, solar, wind as well as bilge pumps or other devices that always remain ON.  A busbar like this helps keep the battery bank free of clutter and limits the need for multiple-lug-stacking.. Fusing is always required at the battery end of an alternator circuit not near the alternator.

The Sterling Power Pro Batt Ultra DC to DC Charger

In our continuing series on CMD’s or Charge Management Devices, this article examines and looks at the benefits of the Sterling Power DC to DC chargers and examines the installations where you may find them useful.

*This article includes the latest Sterling Power Pro Batt Ultra series of battery to battery chargers. The latest model is identified by the green stripe across the top of the face plate label.

Definitions Used In This Article

• Battery to Battery Charger – A DC to DC charge source used for charging one bank of batteries from another bank of batteries
• B2B – Short form for battery to battery charger
• DC to DC Charger – A  battery charger that operates from one DC battery bank to another
• CMD – Charge Management Device/s – Devices used to charge from battery to battery or alternator to battery
  
• Target Bank – The bank the B2B is feeding its output current to
• Source Bank – The bank the B2B is getting its input current from
• LiFePO4 – A lithium-ion battery chemistry – Lithium Iron Phosphate
• LFP – Short hand for LiFePo4
• BMS – A Battery Management System is the protection device for an LiFePo4 battery.

The Sterling Pro Batt Ultra B2B Charger

The above photo illustrates how the Pro Batt Ultra comes out of the box. It includes, as standard equipment, a battery temp sensor for the target bank/battery. The 12V to 12V BB1260 is shown and it’s quite small, much smaller than a 60A shore based charger. Size cab be scaled by comparing it to the battery temp sensor on the left. The small size means it can fit many places a standard AC to DC shore charger may not.

“Why Would I Want or Need a Pro Batt Ultra Battery to Battery Charger?”

The Pro Batt Ultra is the most feature filled, fully programmable DC to DC charge management device in existence today. On top of the cram-packed feature set they are actually priced quite reasonably. Compare what the Pro Batt Ultra is capable of, then compare it to other CMD’s that can’t do half of what the Pro Batt Ultra can do, and you see how good a value this charge management device is. Feature wise, the Pro Batt Ultra actually beats the very good Sterling Pro Charge Ultra shore chargers, and these are very good shore power chargers. The Pro Batt Ultra allows an owner to customize the absorption duration, a very useful feature when dealing with LiFePO4 batteries or even some lead acid and it also has dedicated voltage sensing. These are features not found in many AC chargers even at 3-4 times the price. While we can’t really compare a DC to DC charger to an AC to DC charger, output side charging features count no matter what the charge device is.

When You Would Use a DC to DC Charger vs. Other CMD’s

• Differing On-Board Battery Types/Chemistries – eg: GEL House > AGM Start or AGM Start > LiFePO4 “Drop-In” etc.
• Differing On-Board Bank Voltages – eg: 12V House > 24V Windlass or Thruster Bank or 24V House to 12V Navigation Electronics Bank

What is a Pro Batt Ultra?

Very simply put the Pro Batt Ultra is an extremely full featured battery charger, more so than most AC powered shore chargers you’ll find. That’s it. The only difference between a shore charger and the Pro Batt Ultra is that the Pro Batt Ultra can be powered by another battery bank so that it can be used with all your charge sources to charge the target battery.

Pro Batt Ultra = Buck or Boost

The Pro Batt Ultra can not only “buck” voltage (buck means reduce beyond input) but, unlike most DC to DC chargers, it can also “boost” voltage (boost means increase beyond input). CMD’s such as an ACR/VSR/Combiner, Echo Charger or Digital Duo Charger can only reduce voltage to the target bank and can not increase it. None of the aforementioned CMD’s can float a target bank independently from the source bank but the Pro Batt Ultra can float independently.

For example the Pro Batt Ultra 12V to 12V models can take an input of 14.1V from a source bank and output a higher voltage to charge the target bank that may require 14.8V. Another major plus is the Pro Batt Ultra is available for both like voltage and for mixed voltage vessels where both 12V and 24V banks are installed.

Output Current vs. Input Current: Please be aware that unlike a shore based charger, the Sterling B2B chargers are rated based on max input current. In other words a BB1230 is not a 30A output but rather a 30A input. You will get less than 30A on the output side. This is done so you know the maximum the unit can pull from the “source bank” which is a critical measurement to know. The average efficiency of the Sterling B2B chargers is about 86%, but depends on the input voltage.

Pro Batt Ultra Models Include:

BB1230 – 12V 30A Input to 12V Output

BB1260 – 12V 60A Input 12V Output

BB122470 – 12V 70A Input to 24V 35A Output

BB242435 – 24V 35A Input to 24V Output

BB241235 – 24V 35A Input to 12V 70A Output

BB123670 – 12V 70A Input to 36V 23A Output

BBURC – Remote Display for Pro Batt Ultra

What’s the difference between a DC to DC charger and a shore charger?

An AC powered shore charger needs AC power as the input in order to operate. When at sea this means you’d need an AC generator to run your shore charger. The Pro Batt Ultra B2B does not require AC power and instead requires only a DC input.

The Pro Batt Ultra can be used with any bank that’s being charged by another source such as alternator, *solar or a shore charger.

*If large enough to satisfy the input requirement

What Can it Do Differently Than an ACR/Combiner/VSR, Echo Charger or Digital Duo Charger?

• Can independently float the target bank even when the source bank is in bulk or absorption
• Provides a true multi-stage smart charging algorithm completely independent of source bank
• Has a built in voltage sense circuit
• Has a battery temp sensor as standard equipment
• Can be fully custom programmed including absorption, float, absorption duration on/off points etc.
• Can be activated via ignition excite or automatically by voltage
• Can accept a BMS trigger signal from a LiFePO4 battery BMS
• Can withstand a load dump from a an opened battery switch or a Lithium-Ion BMS Load Dump
• Can reduce or increase the charging voltage to the target bank eg: 14.1V GEL House and 14.7V TPPL AGM Bow Bank
• Can charge a 24V bow bank from a 12V House bank
• Multiple models: 12V input & 12V output, 12V input & 24V output, 24V input & 24V output, 24V input & 24V output
• Is an excellent CMD for use with mixed on board chemistries including lead-acid and LiFePO4
• Is an excellent CMD for charging a 24V bow bank from a 12V house bank.
• Is an excellent CMD for charging a 12V electronics bank from a 24V house bank.
• It is not just a simple “voltage follower” like an ACR, Echo Charger or Digital Duo Charger, it is an actual DC to DC battery charger

Mixed On-Board Bank Voltages:

12V to 24V Charging – BB122470:

The scenario below is quite common on vessels using large DC bow thrusters or larger windlasses or winches. Until now charging a 24V bow bank from a 12V source was a bit of a kludge work around often requiring running a genset and an AC shore charger. The BB122470 is an ideal tool for this type of bank layout where the house bank is 12v and a bow, start, winch or thruster bank is 24V. The Pro Batt Ultra BB122470 makes easy work of this and gives a true multi-stage charge algorithm to the target bank.

In a 12V to 24V situation the BB122470 can be placed closer to house bank, where the input wire needs to be large and handle 70A, and then a smaller gauge 24V output wire can be run to the target bank along with a voltage sense wire and the temp sensor.

24V to 12V Charging – BB241235:

On larger boats it’s not uncommon to have a 24V house bank and a 12V bank to supply 12V marine navigation electronics. In this scenario a BB241235 is being used to charge a navigation electronics bank from a 24V bank of house batteries.

The flexibility of the Pro Batt Ultra is really quite amazing compared to what we’ve had in the past regarding mixed bank voltages.

Typical Installation Consideration for the Sterling Pro Batt Ultra

Wiring

In this image we have a BB1230 being used to charge a start battery from the house. Because the Pro Batt Ultra’s use *pressure plate terminal blocks, meaning bare wire is inserted and the screw tightened, you really want to ensure the wires are properly secured as close to the unit as is feasible. The BB1230 is capable of accepting 6 AWG marine wire and here we’re using 6GA wire.  Each 6 GA wire is secured with wire tie mounts & wire ties to secure each wire within a few inches of the unit. The wiring is also labeled to identify it including the voltage sense wire and the temperature sensor.

*The use of pressure plate terminal blocks should ideally mean they are ABYC compliant and that a “screw” does not impinge upon the bare wire strands. The Pro Batt Ultra’s use internal “plates” that compress the wire and no direct screw is twisting on the wires during torquing making them ABYC compliant.

PRO TIP: With pressure plate terminal blocks, and finely stranded marine wire, it is best to snug the wire, then wait a bit, and snug it once more. The finely stranded wire can slowly compress into shape and the original clamping pressure can decrease.

Because the terminals accept bare wire it is recommended to use tinned wire. Tinned wire is not an ABYC requirement, but it certainly corrodes much less rapidly than bare copper.

Wiring of a Pro Batt Ultra should comply with ABYC E-11 standards

• Fusing input & output positive wires within 7″ of each battery bank (Min fuse size should be 125% of input rating)
• Proper strain relief & wire support
• Chafe protection where necessary
• Wire bundling considerations
• Placement of unit in relation to batteries or moist areas
• Wire labeling
• Use of proper crimp tooling & terminals
• Temp Sensor Placement (negative battery terminal or battery case only)
• Over-Current Protection for Voltage Sense Wire within 7″ of battery positive
• Proper gauge wiring for the amperage (ideally not to exceed 3% voltage drop)

In the wiring example below we have a typical cruising boat installation with all charging feeding the house bank. It is set up for automatic voltage activation. Once the house bank hits 13.2V the B2B will boot up and begin charging the target bank.

As can be seen above the typical marine installation is just 5 total wires or 6, if you purchase the optional remote display:

• Temp Sensor
• Volt Sense
• Output Positive
• Input Positive
• Negative
• Remote Display (optional)

You may be wondering why we took so many man-hours to create all these diagrams? The answer is actually quite simple, the Sterling Power manuals are rather difficult for most owners to make sense of. Even we had to send Charlie Sterling a rather long list to get clarification on some of the wording. Please understand that Charlie is an electrical engineer, and writing manuals for the non-electrical engineer boat owner can be very difficult, to convey clearly, to a DIY. Sterling is not alone in this regard and it is common in the industry. We know the manuals can be difficult because we get the support calls & emails before our customers ever reach out to Sterling Power. Almost always it is just a misunderstanding of the instruction manual, not an actual problem with the product.

Sterling Powers main market for the Pro Batt Ultra is for “caravans“, or RV’s & Trailers to those of us in the USA. In order to cater to this market the product needs to be in compliance with the Euro 6 Emission Standards. In Euro 6 installs the B2B’s are connected to the vehicles starter battery and feed the trailer or RV’s hotel/house battery bank. Due to Euro 6 regulations you can’t really tinker with the alternator and many of these are now controlled by the vehicles CPU to work in concert with regenerative braking etc..

The Pro Batt Ultra allows for regenerative braking / Euro 6 compliance. In short, the stock alternators do a horrible job of charging deeply cycled house banks in the trailer or RV, and you can’t really modify them. The good news for Euro 6 installations is the auto and RV recreational industry typically over-size most alternators, and this results in a very low warranty rate. It also means there is room left over, in terms of amperage, for the B2B charger to pull from.

Bottom Line on the Owner Manual?

For a marine application please ignore the vast majority of the Pro Batt Ultra manual that primarily deals with Euro 6 compliance. We have asked Sterling Power for a Pro Batt Ultra marine only manual but so far no luck.

Input Bank Charge Source Sizing:

Lead Acid Alternator Sizing – Sterling Power recommends that your alternator be sized (based on its SAE output rating) to be at least 30% larger than the B2B unit you choose. In our testing we found 30% to be a bit low for many “stock” alternators and find that double the B2B size means a much cooler running alternator. The reason for this is actually quite simple, you don’t want to tax your small alternator to death. Alternator output also varies based on RPM and winding temp. We see small alternators taxed to death quite regularly on boats.

Unlike automobiles, marine alternators are typically grossly undersized for the work they are expected to do. On the flip side, automotive alternators are typically grossly oversized for the work they are expected to do. As an example the stock alternator in my truck is a 150A Denso hairpin wound unit that’s charging a single G24 starting battery. With every device on max the most I have measured for alternator loads is about 28A. That same alternator, charging a 600Ah house bank, would be at maximum output for close to two hours straight. Most owners of marine engines would kill for a 150A rated alternator instead of the grossly undersized 35A-80A alternator many marine diesels are shipped with.

LiFePO4 Alternator Sizing – If you intend to feed a LiFePO4 battery bank with a ProBatt Ultra, and many do, then Sterling’s suggestion of 30% over-sized, for the alternator, we find to be rather inadequate. We recommend at least double the alternator rating, or larger for the B2B charger. So, if you want to use a 30A B2B on LiFePO4 then you would need an alternator rated at a bare minimum of 60A but preferably one sized for 80A would be much better. Each engine bay, and its heat characteristics, will be different, so predicting how much larger is impossible to really say. In our experiments with stock alternators we find double the B2B input rating for the alternator is a bare minimum.

The best scenario with LiFePO4 is to upgrade your alternator before using a Sterling B2B to feed your LiFePO4 bank.

Shore Charger Sizing – Like the alternator, consideration needs to be given to the demand placed on it by the Pro Batt Ultra. Can the charge source handle it? If the charger can run at 100% of its output rating, and do so continuously, and not all chargers can do this, there is little need to over-size by more than 30%. If however, like some AC chargers, it will limit output if it gets too hot you may want to consider upping it to 40% – 50% larger than the B2B input rating. Again, if feeding LiFePO4, this will need even more examination as demand on the Pro Batt Ultra will be near 100% during the vast majority of the LiFePO4 charge cycle.

Alternative Energy Charging – This will be entirely up to you the owner as to how you choose to use the Pro Batt Ultra. With smaller arrays we generally advise ignition excite, it charges start or bow bank when the engine runs, but if you have a large array, voltage excitation can certainly work.

Just try to ensure your charge sources can exceed the demand placed on the B2B by the target bank. In situations where the B2B is charging only a start battery, this is not going to be a big deal, start batteries require very little charging hence little demand on the source bank charger, but as the target bank requires more current, such as a bow-thruster bank or LiFePO4 it can cause B2B on/off cycling so charge source sizing becomes more critical.

Ignition Excitation

For some situations, such as LiFePo4, or a low current PV system, an owner may want the B2B to run when the engine is turned on, even if the input voltage is below the “automatic” turn on point of 13.2V. This is called “ignition excitation” or “key-on excite“. If ignition excite is used the unit can boot up and start charging a target bank with input voltages as low as 10V. The image below shows where the +12V ignition feed would be wired to. To use “Ignition Excitation” all that is required is one wire from the run position of the engine switch.

In this image we can see the ignition terminal of the B2B connected to the “run” position of the engines key switch. When the engine is fired up, there is a brief delay, and then the Pro Batt Ultra will boot up and begin charging the target battery.

Voltage Excitation / Activation

The Pro Batt Ultra (green stripe models) comes out of the box ready to be used in automatic voltage activation mode. By not using the ignition terminal the unit will only turn on once voltage has attained the turn-on voltage of 13.2V, and a short delay timer clock has been run out. The timer delay is to prevent on/off cycling as the bank approaches the voltage turn-on level. The on voltage and cut off voltage can be adjusted up or down but there will always be a 0.2V spread between the ON & OFF points. An adjustable turn-on voltage can be handy when dealing with a LiFePo4 house battery, that may be the “source bank”, and will have a significantly higher resting voltage than lead acid batteries do. In this case increasing the automatic voltage activation point to 13.5V – 13.6V will mean the B2B only boots when the LiFePo4 battery is actually being charged, but don’t forget that the OFF voltage is always 0.2V lower than the ON voltage.

For example; ON = 13.2V and OFF = 13.0V   or   ON = 13.6V and OFF = 13.4V

What about quiescent current draw?

The nice thing about the Pro Batt Ultra is that it automatically puts itself to sleep when input voltage is below the TURN OFF voltage set point (13.0V as it ships). If you fit a remote display the remote also goes to sleep. The quiescent draw or parasitic load that’s placed on the source battery, when the unit is sleeping, is just 1mA! 1mA = 0.001A. In an entire week asleep on standby the unit uses just 0.168 Ah’s. Pretty amazing really.

Alternative Uses for the ProBatt Ultra – LiFePO4

With LiFePO4 drop-in batteries now being heavily marketed, and prices falling to an acceptable level for many boaters, there are issues that can arise that need to be addressed before you can simply “drop them in“..  These issues involve “drop-in” type LiFePO4 batteries that feature a 100% sealed non-communicable internal  BMS (battery management system). The problem is not how the BMS manages the battery, it is in its ability to disconnect the battery from the vessel & charge sources. With most drop-in LFP batteries this can happen without any advanced warning.

A LiFePO4 drop-in batteries internal BMS can disconnect for the following reasons:

• Cell Over Voltage
• Cell Under Voltage
• Cell Temperature
• BMS Temperature
• BMS Current Limits Exceeded

If there is a bad cell, temperature too high, too much charge current, a glitch in the charging voltage settings or a cell imbalance issue creating an over-voltage condition, the battery will physically disconnect itself from the vessel. Most drop-in LiFePO4 batteries can disconnect themselves with no advanced warning to the vessel occupants. This is called a load disconnect or load dump.

A load disconnect or load dump is something a lead acid battery can’t physically do on its own, so this, by definition makes “drop-in” LFP batteries not so “drop-in” because we now need a ways to ensure our alternator or inverter/charger is not suffering load dumps. Of course you don’t need to take out word for it, so how about Balmar, the worlds largest specialty marine performance alternator and regulator manufacturer.

Sure, many an owner has moved a battery switch with the alternator charging and had the destroyed alternator to show for it but the battery did not do this without warning, and the owner made a simple, and often fatal to the alternator, mistake. If a BMS disconnect / load-dump occurs, when charging with an alternator, or even a large transformer based inverter/charger, the resulting *voltage transient,  can damage the charge source and also what ever is connected to the DC bus/system such as sensitive marine electronics.

*Voltage Transient – What occurs when a charge source such as an alternator is suddenly disconnected from the load (battery). The current now has nowhere to go sending the voltage through the roof. When the load (battery) is suddenly disconnected the voltage skyrockets to damaging levels in milliseconds.

During normal operation the alternator operates normally: (most drop-in batteries have the BMS disconnect on the negative side of the battery)

In a fault condition this is what can happen to the alternator:

What a load dump can look like:

How does the Sterling ProBatt Ultra play into this?

The unique aspects of the ProBatt Ultra are in its ability to:

1.  Have a charge profile that is suitable for LiFePO4 (many lead acid charge sources are not ideally suited for LFP)
2. Can withstand a load dump

This image below is why, when discussing the ProBatt Ultra, I prefer to use the terms SOURCE BANK and TARGET BANK. As can be seen we have reversed the way we would typically use the ProBatt Ultra in a lead acid installation and now the start battery is our  source bank and the ProBatt Ultra feeds the LiFePo4 bank or target bank.

“But RC a BB1260 is not enough charge current for my LiFePO4 system?”

Not a problem, simply parallel two or more Pro Batt Ultras together, providing your input charge sources are 30% larger or more, and you can now charge at significantly higher amperage.

While the ProBatt Ultra has been designed to withstand a load dump, other items on-board your vessel, connected to the loads bus, may not be. This is why we recommend a Sterling Alternator Protection Device for every vessel or RV etc. that has drop-in LFP batteries. The Alternator Protection Device clamps the transient to a safe level. We have tested these in our shop, on our alternator test bench, to 130A and not been able to kill one. Installation is very simple & straightforward two wire connection done close to the alternator B+ & B- terminals as shown below:
If you’re installing LFP drop-in batteries a Sterling Power Alternator Protection device is a must-have item: Purchase an Alternator Protection Device

Remote Display

Like any charge management device they are often installed where you can’t see them, and don’t know what is really going on. The optional BBURC is the remote display for the Pro Batt Ultra. It displays charge stage, input voltage, output voltage, unit temperature and battery temperature. It can also be set to alarm a user of a fault condition.

The words remote displayare meaningful because the BBURC is, unfortunately, not for programming the unit. Sterling Power keeps programming at the B2B charger so folks can’t fiddle with the remote and change settings. Little kids love to push buttons. Programming via the remote would be nice but I do fully understand the hesitation. Perhaps in the future there will be a lock-out on the remote to stop roaming fingers from changing settings?

Pro Batt Ultra Likes & Dislikes

No product is 100% perfect and we won’t pretend the Pro Batt Ultra is, but it is quite good and certainly a “best in class” product. Here at Compass Marine Inc. we are big fans of the Pro Batt Ultra because it can do things no other charge management device can.

Likes:

• Dedicated Voltage Sensing
• Adjustable Absorption Duration
• Forced Float Option
• Optional Remote Display
• 1 mA Parasitic Draw When in Sleep Mode
• Can Equalize
• True Fully Independent Multi-Stage Charging Output
• Buck or Boost
• 12V & 24V Mixed Voltage Models
• Compact Size for the Amperage
• Temp Sensor Included
• Can Withstand a Load Dump
• Ignition Excite Option
• Fully Custom Programmable
• Easy to Install
• Best in Class Product
• Pricing is Very Competitive
• Good for Drop-In LiFePo4 Charging
• 2 Year Warranty (many other DC to DC chargers are 90 Days)

Dislikes:

• Owners Manual
• Programming is a Bit Kludgy
• Terminal Strip Orientation for Temp/V-Sense/BMS is Awkwardly Located
• Fan Noise (only when working hard)
• Programming Buttons Vary in Location By Model

Overall the Pro Batt Ultra is a very unique product that no other company even comes close to. The Pro Batt Ultra is a product we are proud to offer to our readers in the MarineHowTo.com Web Store. Please remember the web store at MHT supports this site and keeps it FREE!

BB1230 – 12V 30A Input to 12V Output

BB1260 – 12V 60A Input 12V Output

BB122470 – 12V 70A Input to 24V 35A Output

BB242435 – 24V 35A Input to 24V Output

BB241235 – 24V 35A Input to 12V 70A Output

BB123670 – 12V 70A Input to 36V 23A Output

BBURC – Remote Display for Pro Batt Ultra

Happy boating!

Raymarine SeaTalk 1 to SeaTalk^ng & NMEA 2000

We get asked this electronics question more than just about any other, from customers who have a perfectly operating SeaTalk 1 network and want to add the SeaTalk 1 data to the NMEA 2000 bus. The article deals specifically with older Raymarine products that operate on the proprietary SeaTalk 1 network.

The conversion from SeaTalk 1 to SeaTalk^ng / NMEA 2000 is actually pretty simple once you have the Raymarine E22158 converter kit:

Site Plug:  The SeaTalk 1 to SeaTalk^ng  Converter Kit can be purchased from the MarineHowwTo.com web store. Purchases from our web store help keep this site FREE!

You can purchase the Raymarine SeaTalk 1 to SeaTalk^ng  Converter Kit here: Raymarine SeaTalk 1 to SeaTalk^ng  Converter Kit (LINK)

What You’ll Need:

• Raymarine E22158 SeaTalk 1 to SeaTalk^ng conversion kit (see image above)
• A male or female SeaTalk^ng to NMEA 2000 drop cable:
• Male SeaTalk^ng to NMEA 2000 = A06046
• Female SeaTalk^ng to NMEA 2000 = A06045

A lot of boat owners don’t realize that Raymarine’s SeaTalk^ng is essentially NMEA 2000 that is using Raymarine’s proprietary SeaTalk^ng cables/connectors. Once your SeaTalk 1 data is converted into SeaTalk^ng / NMEA 2000 the conversion & connection to the rest of the vessels NMEA 2000 bus is much easier.

The SeaTalk 1 to SeaTalk^ng converter is actually a small electronic signal converter that has operational software doing the conversion. This converter is not just a busbar or fancy terminals strip, as some have described it. The device below is actually a small processor running software.
WARNING: We have seen a number of individuals physically damage equipment or disable a complete NMEA 2000 system by trying to hard-wire an older SeaTalk 1 network to SeaTalk^ng or NMEA 2000 networks.

YOU CAN NOT DO THIS!

Getting from SeaTalk 1 to SeaTalk^ng / NMEA 2000 requires a proper electronic language conversion.

Connection to a standard NMEA 2000 network will look similar to this:

In the image above we are connecting a customers SeaTalk 1 instruments to an NMEA 2000 Garmin chart plotter. This wiring puts the SeaTalk 1 data onto the NMEA 2000 Garmin chart plotter..

The total cost for this upgrade will run you slightly over $100.00 in order to get your SeaTalk 1 data converted over to NMEA 2000 based electronics.

Important Notes:
#1 If the E22158 converter is used only as a drop device, to port SeaTalk 1 over to NMEA 2000, and is not at the end of a back bone, or in a backbone, you would not use any terminators in the blue ports.

#2 If the E22158 converter is the end of a back bone, as shown here, a blue terminator would be used. Terminators are only used at either end of a back bone! For empty drop ports you can use Raymarine blanking plugs in the SeaTalk^ng drop ports or NMEA 2000 blanking caps to protect any unused future expansion ports on an NMEA 2000 bus.

#3 IMPORTANT: Only two terminators are allowed per NMEA 2000 network. One terminator at each end of the back-bone. We’ve seen DIY installations using numerous terminators and no, the systems were not working correctly.

#4 If the SeaTalk 1 network was already powered, and you are connecting to an already powered NMEA 2000 network, you’ll need to disconnected the red power feed wire for the SeaTalk 1 network. Having multiple sources of power can create a potential for ground loops, if not wired correctly.

Good luck and happy boating!

How we Tested the New Balmar SG200 Self Learning Battery Monitor

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The Balmar SG200 is a revolutionary new battery monitor in that its feature set, capabilities and algorithms are a brand new concept in battery monitoring.

The Balmar SG200 is a self-learning battery monitor which was 100% developed in-house by CDI/Balmar. Compass Marine Inc. / MarineHowTo.com worked quite closely with CDI/Balmar, along with other Balmar dealers, to identify what we wanted to see in a fresh new battery monitor. One thing we have grown to appreciate about CDI/Balmar is their willingness to identify what their dealers see as credible needs before pursuing a project.

While every feature we wanted to see, in a battery monitor, did not make it into the SG200, what we do have is a revolutionary new self-learning battery monitor that is flexible, remarkably accurate and incorporates a brand new SoH or State of Health calculation. SoH allows you to know where your bank stands in relation to the programmed or rated Ah capacity and has been previously non-existent in traditional Ah counters.

What is SoH?

SoH is a new feature in the SG200 that compares your banks current state of health to its “as new” factory 20-hour Ah capacity rating.

By industry standards batteries are considered dead when they can no longer deliver at least 80% of their factory rated Ah capacity. While 80% or lower does not mean they are “actually dead” it is where the battery industry sets the low safe level for continued use of deep-cycling batteries.

For setting up the SG200, let’s assume you have a 100Ah rated battery. You would simply program 100Ah into the SG200, regardless of the batteries age or current condition. Over time the *SoH will hone in and find your “percentage of new” state of health of the battery or bank. If the screen reads 77% SoH, after it has had ample time to learn the bank, then this would be an indication that the batteries are nearing end of life and replacements should be on the horizon.

*SoH is a function that only works with banks that are actively deep-cycled. In other words if you purchase an extra shunt for a bow or start bank don’t expect an SoH indication as the SoH feature is specifically engineered for banks that are cycled eg; house banks.

If you’re a coastal cruiser then this number may not be all that alarming but if you venture across the ponds you’ll want to give your bank much more serious replacement consideration when you start getting into the 70’s as a percentage of new.

Development

Like all good things the SG200 did not just happen over-night. All told, it took nearly 4 years to get from ideas on paper to an Alpha level product for testing. Here at Compass Marine Inc. we’ve conducted nearly an entire years worth of testing the SG200. It’s actually still on-going every time we come up with a new way to possibly trip it up or we come across a battery we believe can trip it up. Like most products the SG200 did not come out of the lab “prime-time” ready and a number of software tweaks were made along the way before the finished product began shipping. The engineers at Balmar were tremendous to work with and they responded quickly. While lab testing can’t always predict every single real-wold situation it can be used to develop a platform to start from.  Add in a learning algorithm, and the ability to update firmware for future proofing, and you’ve got a very simple to use product.

SoC, SoH, Amperage & Minutes Left (at current load)

Recently, while up in Maine for a boat show, Chris Witzgall, Balmar’s Product Manager, stopped by our shop to get an idea of how we tested the SG200. Knowing Chris is far better than us with a video camera, we decided to take a different approach to our normal long diatribe of words and photos. We hope this video sums up & conveys how we tested the SG200 and why we were so interested to see yet another battery monitor hit the market.

What we like about the Balmar SG200:

• Multiple shunts can be used with one display to monitor multiple on-board battery banks
• The smarts or computer chip of the SG200 are housed inside the newly designed “Smart Shunt“
• SoH (State of Health) calculation lets you know when your bank is no-longer in a healthy state
• SoC accuracy is quite good within half a dozen deep cycles and continues to get more accurate as time goes on
• Self-Learning means no more cumbersome programming
• Displays – SoC, SoH, Charge/Discharge Current, History, Faults & Alerts
• Supports battery banks up to 1300Ah
• Bluetooth capability via optional Bluetooth gateway
• Firmware changes can be updated via Bluetooth
• Supports Flooded Lead Acid, AGM, TPPL AGM, Carbon Foam AGM, GEL & *LiFePO4
• Supports banks of 12V to 48V
• SoC accuracy as good as 97% in just a few cycles
• Auto-Calibrating
• Remains accurate even as a battery ages
• Less money than the SoC only Smartgauge
• Our customers want simple, not complex, and the SG200 is simple, easy and accurate

*LiFePO4 – The SG200 may not work with certain “drop-in” Chinese LiFePO4 batteries. The SG200 has been tested with Lithionics, Battle Born, Relion, Mastervolt and numerous DIY built batteries with BMS protection operating on the positive bus.

What about Installation?

While the SG200 is a shunt based device, once you understand where the shunt needs to be, as close to battery negative as possible, and that wires that by-pass the shunt (sneaker wires) are not allowed, the installation is very straightforward.

The general installation is simple:

#1 Create a short negative jumper wire to go between the bank negative terminal and the battery side of the SmartShunt

#2 Wire all negative wires on the vessel to the “Cable” or “Load” side of the SmartShunt. Adding a heavy duty busbar can help with this

#3 Mount the display. It fits into a 2 1/16″ hole

#4 Run the SmartLink Cable then install the Deutsch terminal on the end and plug it into the display & SmartShunt

#5 Connect the orange wires to their respective banks (if applicable) and fuse within 7″ of battery positive.

#6 Double check that you have NO DC NEGATIVE WIRES ON THE BATTERY SIDE OF THE SHUNT!

#7 Pull the fuse from the red power + wire and connect it to the banks positive terminal.

#8 Reinstall the fuse and when the SG200 boots up program it with your banks information.

When wiring the Balmar SG200’s SmartShunt you may want to purchase a heavy duty busbar, as shown below, to collect all the vessels DC negatives.

Patience is a Virtue:

TIP: Once your SG200 is installed & programmed please be patient. The SG200 requires your bank to be deeply-cycled quite a few times in order for SoC and SoH to hone in. The deeper these cycles are, the faster the SG200 can learn the bank. Don’t be afraid to take your lead acid bank to 11.7V, if you want to speed up the learning process, just be sure you can recharge to 100% on the next cycle. Shallow cycling will just prolong the time it takes for the SG200 to “learn” bank behavior such as SoH.

Quote: “Rod, I have had my new SG200 connected for almost four weeks and am still getting three dashes for SoH? We have not been able to leave the dock yet but was hoping to know my banks condition before we do?”

***The SG200 can’t learn SoH while tied to a dock charging 24/7***

The SG200 also cannot determine SoH while not charging and resting. To test this, we connected a lead acid battery to the SG200 and let it sit for two and a half months, with no charging or discharging, other than the SG200’s connection to the battery. At the end of 2.5 months the SG200 was still showing three dashes — for SoH. Bottom line? The SG200 is smart enough to know whether you’re cycling or not. The good news is that the SoC prediction, at the end of 2.5 months, was accurate to within 3%, while just sitting there.

SoH Behavior:

At first the SG200 will show three dashes – – – for SoH. It will continue to do this until enough cycles have been completed, and they are deep enough cycles. You’ll want to discharge to at least 50% SoC. Once the three dashes disappear it will start to show a preliminary SoH. If your boat is dockside for a while SoH won’t begin to display until the bank starts being actively cycled. Unlike SoC, which responds more rapidly, SoH is not intended for rapid updating and really needs to learn your banks behavior. Expect upwards of a dozen or more deep-cycles for SoH to be accurate. Be patient!

Insider Guidance:

Please do not make the mistake of comparing the SG200 to a traditional Ah counter. They are not the same at all and not even close to being the in the same category ease of use wise. The SG200 is using multiple technologies to track the bank and doing so in a multiple cross-check fashion. The SG200 can measure and cross-check; battery impedance, internally stored battery behavioral models, voltage – measured many thousands of times per second, coulomb-counting, amperage/load, time *etc. and a self-learning algorithm to bring it all together.

*Etc. – There are other measurements & trade secrets going on inside the SG200 that we cannot publish.

The unique aspect of the SG200 is that each of these data measurements is cross-checked and is compared to the others so that no single measurement can control or skew the data. The SG200 can track both SoH and SoC and to do so very accurately without any cumbersome programming or manual re-sync being necessary.

The SG200 is the most accurate battery monitor for SoC & SoH we’ve tested here at Compass Marine Inc..

As I sit here typing this we have a Trojan SCS-225 130Ah flooded deep cycle battery on the test bench. It recently tested at 99.4Ah or 76.4% SoH. As can be seen the SG200 is reading 76% SoH. It honed in this accurately in just 10 deep cycles. This is about as perfect a prediction of SoH and you can get without an expensive or time consuming 20 hour test. This is rather amazing performance.

SG200 Do’s & Don’ts:

• Do mount the Smartshunt as close to battery banks negative terminal as possible – less than 12″ is preferred
• Do use the largest gauge wire you can between the Smartshunt and battery negative terminal
• Do coat the shunt bolts or nuts with an anti-thread galling compound such as Tef-Gel. They are SS.
• Do use crimping tools that result in the lowest resistance for any wire terminations
• Do aim for the lowest possible voltage drop in your bank & shunt wiring.
• Do connect the red fused wire directly to the battery banks positive terminal *only.
• Do install the fuse for the red wire as the absolute last item installed.
• Do wire parallel or series/parallel bank for optimal intrabank balance.
• Do be patient. The Sg200 can’t work miracles, it needs to learn your bank during deep-cycling use.
• Do cycle deeply on the first few cycles. The deeper you go the faster the SG200 will learn your bank
• Do set it and forget it.
• Do not keep changing settings hoping for it to speed the learning process, all you’re doing is slowing it down.
• Do not depower or disconnect the SG200 from the battery, unless during winter storage.

*For LiFePO4 this decision will need to be weighed by the owner as to place it on the load side of a BMS switch or not. Drop-In LFP you have no choice in this matter. The SG200 will perform best with a direct red fused wire connection to the battery banks positive terminal.

Before you consider an Ah counting battery monitor, one that requires copious amount of human interaction/programming, to keep them accurately tracking the battery, consider the Balmar SG200 and let it do the work for you.

Good luck and happy boating!