LiFePO4 'Starter' Batteries ???

[tpenfield]

Greetings,

A question for future considerations . . .

I am seeing a few so-called LiFePO4 'Starter' Batteries come on the market, claiming to be "plug 'n play", and I know some marine engine manufacturers are listing them as OK to use with engines (mostly outboard engines I believe) that have smart alternators.

I am wondering if/when these starter batteries would be appropriate for starting marine engines with dumb alternators? I have a boat with twin V8 sterndrive engines (Mercruiser 6.2L with all the fancy electronic controls - aka Digital Throttle & Shift, and Axius Joystick docking). I believe the alternators are of the 'dumb' variety . . .

As I understand it, there are a few issues to be concerned about . . .

• Cranking amps (which instantaneously can be about 500 amps and then settle in at about 100-150 amps while cranking the engine.
• Bulk charging of the batteries placing excessive load on the dumb alternators.
• BMS shutoff of the charging when the LiFePO4 reaches full charge or otherwise goes into protection mode . . . causing the alternator to voltage spike.

I wonder if these 'starter' batteries really have the bases covered, or if you still need additional components to supplement their use as starter batteries for large/larger engines?

Anyway, not a concern for me right now, as I have new LA starter batteries in my boat, but something to consider for the future.

 

[wpns]

Following!

Our big boat has two new AGM batteries that aren’t doing well (upgrade from FLA truck batteries might not have been the best idea but I wasn’t in the loop on that) but starts every time with a 20W panel and PWM controller.

Our little boat works fine only when the AC charger is connected (no room for solar). Yes, needs new battery but not for a kilodollar.

 

[markpj23]

Greetings,

A question for future considerations . . .

I am seeing a few so-called LiFePO4 'Starter' Batteries come on the market, claiming to be "plug 'n play", and I know some marine engine manufacturers are listing them as OK to use with engines (mostly outboard engines I believe) that have smart alternators.

I am wondering if/when these starter batteries would be appropriate for starting marine engines with dumb alternators? I have a boat with twin V8 sterndrive engines (Mercruiser 6.2L with all the fancy electronic controls - aka Digital Throttle & Shift, and Axius Joystick docking). I believe the alternators are of the 'dumb' variety . . .

As I understand it, there are a few issues to be concerned about . . .

• Cranking amps (which instantaneously can be about 500 amps and then settle in at about 100-150 amps while cranking the engine.
• Bulk charging of the batteries placing excessive load on the dumb alternators.
• BMS shutoff of the charging when the LiFePO4 reaches full charge or otherwise goes into protection mode . . . causing the alternator to voltage spike.

I wonder if these 'starter' batteries really have the bases covered, or if you still need additional components to supplement their use as starter batteries for large/larger engines?

Anyway, not a concern for me right now, as I have new LA starter batteries in my boat, but something to consider for the future.

You have correctly identified the issues with so-called 'drop-in' LFP batteries. The new ones rated for starting battery current loads have the exact same charging constraints / challenges. So the answer to your question is "Yes, you still need additional components...."
Fortunately the solution & additional components are not that expensive nowadays. A good DC-DC charger and alternator no-load protection device can be had for around $300. A good regulator can probably turn your 'dumb' alternator into a smart one for about the same amount.

 

[wholybee]

They are mostly likely just fine as starter batteries. If you also use them for "house" loads, maybe/maybe not.
The first consideration is that many new "dumb" alternators do have a temperature sensor, which solves one of the biggest issues.
Second, as a start battery, it is always full. Starting an engine, although high Amps, uses very little battery capacity. So, the alternator is going to work for a very short time.
Third, if the battery disconnects, it will do so at the very top of the charge, when there shouldn't be very much current being drawn, so a voltage dump isn't likely an issue.
The possible is becomes if you use it as a house battery as well, and draw it down to a low state of charge. Now, the alternator will be working hard for much longer (but still not a problem if it has a temp sensor) and if it for some reason disconnects while charging hard at a lower state of charge, then you have the voltage dump issue. But, that isn't really likely, as the disconnect usually happens at the very top of the charge, when current should be low.

 

[Supervstech]

A few issues i can think of for a drop in battery use as starter is, bms dropping voltage to zero if a cell reaches disconnect voltage.
Alternators running without a battery attached can fry vehicle electronics.
Also, LFP does not like being held at 100% charge for long periods.
Depending on alternator voltage regulator, 14.5V could be fed, relying on the BMS to stop overcharge.
This can cycle fail the bms as well.

 

[wpns]

They are mostly likely just fine as starter batteries. If you also use them for "house" loads, maybe/maybe not.
The first consideration is that many new "dumb" alternators do have a temperature sensor, which solves one of the biggest issues.
Second, as a start battery, it is always full. Starting an engine, although high Amps, uses very little battery capacity. So, the alternator is going to work for a very short time.
Third, if the battery disconnects, it will do so at the very top of the charge, when there shouldn't be very much current being drawn, so a voltage dump isn't likely an issue.
The possible is becomes if you use it as a house battery as well, and draw it down to a low state of charge. Now, the alternator will be working hard for much longer (but still not a problem if it has a temp sensor) and if it for some reason disconnects while charging hard at a lower state of charge, then you have the voltage dump issue. But, that isn't really likely, as the disconnect usually happens at the very top of the charge, when current should be low.

A couple of details: Some outboard engine alternators will destroy themselves if not connected to a battery (as when the battery gets overcharged and disconnects itself). Most boats have bilge pumps, which can run the battery down in rainy weather (we got 3.2+ inches of rain yesterday!). Yeah, I know, easy solution, multiple thousand-dollar batteries with selector switches. On a 17-foot Whaler?

Anyway, lots of ifs/ands/ors/buts, depending ons the BMS to protect the battery isn't recommended, IMHO not ready for prime time yet...

 

[tpenfield]

Good comments so far. Thanks folks !

I may try this at some point if my SLA starter batteries get 'tired'.

 

[tpenfield]

Looks like most of the decent sized 'starter' LFP batteries are $500+ . . . probably because of the BMS being able to handle the amps. So, not a thing right now from a cost perspective, but consideration for future as prices come down.

 

[patrickparrott]

I have been working on the Lifpo4 battery issue with Dakota starter and deep cycle trolling motor and starter batteries ever since I bought my new 17' 8" Maverick Flats skiff in 2022. I have had some success but am not out of the woods completely yet. I use two 60ah starter batteries and one 54ah trolling motor battery. The 12v trolling motor is on a separate circuit and is only charged by a Noco 3x10a charger when in my garage. I get excellent run times and it has never failed me or shut down on me. The boat is very light (1200lbs.carbon fiber with motor and fuel). The starter batteries are a completely different story. I am experiencing the same issues as others on this forum are describing. I have tried to use them as a drop in battery, but I do not think that is possible. When using only battery #2 while cruising back to the launch ramp It kept shutting down. I suspect that the BMS entered protection mode while the alternator was trying to stuff it with more charge. The charge level prior to shut down was erratic and bouncing between 14v and 18v. I called Dakota and they felt that it may not have received the change made to the upper level of the BMS shut off during the manufacturing process. They would replace it or I could use a DC/DC converter to solve the problem. I agreed, chose a new battery and shipped the battery back to them for a replacement. I expect it to arrive tomorrow. Meanwhile, battery #1 starts to show the same erratic voltage behavior but no shutdown as battery #2 had. I always use an Engel refrigerator/freezer and turn it on when I leave the house to keep the drinks cold up in the front hatch. It draws around 2a when the compressor is running. This time I left it off fearing no backup starter battery. Evidently that 2a draw was keeping #1 from topping out and I began to have the erratic behavior. I doubt that Dakota has solved the problem with by changing the upper limit on the BMS because it's really the alternator circuit that needs a design change. I'm going to install the replacement battery and see what happens. I suspect that I will be purchasing the Victron 12/18 Orion smart converter soon. Please make any comments about this post or your experiences that you have. I intend to solve this problem. My fishing comfort and safety depend on it!

 

[wpns]

A good DC-DC charger and alternator no-load protection device can be had for around $300.

Will something like https://balmar.net/alternator-protection-modules/ APM-12 (just under $80 at West Marine) keep the alternator from high-voltage damage if there's no other load? Where does the power go? Surely that little box isn't going to be good for many watts...

 

[wpns]

I have been working on the Lifpo4 battery issue with Dakota starter and deep cycle trolling motor and starter batteries ever since I bought my new 17' 8" Maverick Flats skiff in 2022. I have had some success but am not out of the woods completely yet. I use two 60ah starter batteries and one 54ah trolling motor battery. The 12v trolling motor is on a separate circuit and is only charged by a Noco 3x10a charger when in my garage. I get excellent run times and it has never failed me or shut down on me. The boat is very light (1200lbs.carbon fiber with motor and fuel). The starter batteries are a completely different story. I am experiencing the same issues as others on this forum are describing. I have tried to use them as a drop in battery, but I do not think that is possible. When using only battery #2 while cruising back to the launch ramp It kept shutting down. I suspect that the BMS entered protection mode while the alternator was trying to stuff it with more charge. The charge level prior to shut down was erratic and bouncing between 14v and 18v. I called Dakota and they felt that it may not have received the change made to the upper level of the BMS shut off during the manufacturing process. They would replace it or I could use a DC/DC converter to solve the problem. I agreed, chose a new battery and shipped the battery back to them for a replacement. I expect it to arrive tomorrow. Meanwhile, battery #1 starts to show the same erratic voltage behavior but no shutdown as battery #2 had. I always use an Engel refrigerator/freezer and turn it on when I leave the house to keep the drinks cold up in the front hatch. It draws around 2a when the compressor is running. This time I left it off fearing no backup starter battery. Evidently that 2a draw was keeping #1 from topping out and I began to have the erratic behavior. I doubt that Dakota has solved the problem with by changing the upper limit on the BMS because it's really the alternator circuit that needs a design change. I'm going to install the replacement battery and see what happens. I suspect that I will be purchasing the Victron 12/18 Orion smart converter soon. Please make any comments about this post or your experiences that you have. I intend to solve this problem. My fishing comfort and safety depend on it!

Maybe your solution is a traditional LA starter battery and a DC-DC charger to keep a lithium house battery charged? Just need to pick (or set) a power level for the DC-DC charger that won't overtax the alternator, and that's probably engine-dependent...

 

[patrickparrott]

Will something like https://balmar.net/alternator-protection-modules/ APM-12 (just under $80 at West Marine) keep the alternator from high-voltage damage if there's no other load? Where does the power go? Surely that little box isn't going to be good for many watts...

Thanks for the good suggestion. I will begin research and call Balmar about this product. Some outboard alternators already have smart alternators in them. Some have also added temp sensors to prevent overcharging the battery and heating up the alternator. I'm not sure what this 2yr old motor has. Balmar does not list one of these for a Yamaha outboard. You have me thinking. Dakota seems to feel that the Victron smart Orion takes care of it. If its a smart alternator the circuitry lowers the charge when the either the temp of the alternator goes up or through sensing circuitry through the battery wiring.

 

[patrickparrott]

Maybe your solution is a traditional LA starter battery and a DC-DC charger to keep a lithium house battery charged? Just need to pick (or set) a power level for the DC-DC charger that won't overtax the alternator, and that's probably engine-dependent...

Yes, that voltage level can be adjusted in the Orion smart converter. Obviously, Yamaha has done something to make sure that the sudden spike when the shutdown occurs doesn't damage the alternator diodes. It's happened about 7 times now. I do believe that the hybrid solution will work fine, but I also think that there is a possibility that all lithium can be set up to work fine too. And I need to have a look at what the new Victron Orion might help with. It just came out on the market. The boat goes in storage in 4 weeks until next January, so I have some time to find the answer after the Dakota converter solution sees a tryout.

 

[wholybee]

That you see voltage bounce around between 14-18 volts is concerning. That actually sounds like the battery had already gone into protection. If the battery had not gone into protection, then the voltage would not fluctuate, but would sit at the voltage of the battery. In protection, the battery would still power everything, just not accept any further charge, so you might not otherwise notice anything wrong. The fluctuation to 18V would happen as the alternator is generating power with nowhere for it to go.

What voltage does the alternator charge to when connected to a lead-acid battery? What voltage is the LFP battery when it is fully charged with an LFP AC charger? I don't know what the HVC voltage for the Dakota battery is, but it is probably about 14.6V. You would need to find a way to limit the voltage from the alternator to less than this. Typical for an inboard alternator would be around 14.4V, and thus should work just as a drop in. If adjustable, the ideal voltage is around 13.8V. I have no idea what voltage an outboard alternator charges at.

What is the max current output of your alternator? You will not get a large load dump voltage spike unless there is a lot of current flowing at the time it happens. A small alternator isn't going to create a large voltage spike, and neither will there be one if the battery is fully charged when it disconnects, because current into a fully charged battery is low. The 18V might actually be a load dump from the battery disconnecting. That is small enough, I doubt the Balmar APD would even attempt to squash it.

 

[tpenfield]

Based on Patrick's experience, it looks like stand-alone LFP starter batteries are not ready for prime time. It seems like the battery(ies) would need a DC-DC charger to buffer the alternator . . . and probably one of those Balmar modules.

 

[wholybee]

Based on Patrick's experience, it looks like stand-alone LFP starter batteries are not ready for prime time. It seems like the battery(ies) would need a DC-DC charger to buffer the alternator . . . and probably one of those Balmar modules.

I disagree. Although they might not be suitable for outboard engines with smaller less sophisticated alternators. But for inboard engines or RV's etc. they should be fine. Many people are already using non-starter rated drop-ins connected to engine alternators without problems. Only they aren't using them for starting. That part is proven to already work. Adding a BMS that will handle the start current should make them perfectly acceptable, provided the alternator has good regulation, temperature sensors, and can output reasonable current. Which most modern alternators on an inboard do.

 

[Rocketman]

I don’t know about Marine…
But my brother installed a lithium battery in his side by side ATV. A short time later (a couple of hours on the atv), it died and then they noticed “smoke” coming from the battery. He pulled the battery out (very hot and venting) and started to walk back to cell phone range.

My guess is the dumb alternator kept pumping volts into the battery (don’t know if it has a bms), and that caused a run-a-way issue. (His old lead battery died before it should have as well - 2years).

The battery was sold at an auto parts store. He got his money back.

Much thought/equipment needs to be on the charging system before I would use it for a starter battery - but there are ways to do it.

 

[markpj23]

I have been working on the Lifpo4 battery issue with Dakota starter and deep cycle trolling motor and starter batteries ever since I bought my new 17' 8" Maverick Flats skiff in 2022. I have had some success but am not out of the woods completely yet. I use two 60ah starter batteries and one 54ah trolling motor battery. The 12v trolling motor is on a separate circuit and is only charged by a Noco 3x10a charger when in my garage. I get excellent run times and it has never failed me or shut down on me. The boat is very light (1200lbs.carbon fiber with motor and fuel). The starter batteries are a completely different story. I am experiencing the same issues as others on this forum are describing. I have tried to use them as a drop in battery, but I do not think that is possible. When using only battery #2 while cruising back to the launch ramp It kept shutting down. I suspect that the BMS entered protection mode while the alternator was trying to stuff it with more charge. The charge level prior to shut down was erratic and bouncing between 14v and 18v. I called Dakota and they felt that it may not have received the change made to the upper level of the BMS shut off during the manufacturing process. They would replace it or I could use a DC/DC converter to solve the problem. I agreed, chose a new battery and shipped the battery back to them for a replacement. I expect it to arrive tomorrow. Meanwhile, battery #1 starts to show the same erratic voltage behavior but no shutdown as battery #2 had. I always use an Engel refrigerator/freezer and turn it on when I leave the house to keep the drinks cold up in the front hatch. It draws around 2a when the compressor is running. This time I left it off fearing no backup starter battery. Evidently that 2a draw was keeping #1 from topping out and I began to have the erratic behavior. I doubt that Dakota has solved the problem with by changing the upper limit on the BMS because it's really the alternator circuit that needs a design change. I'm going to install the replacement battery and see what happens. I suspect that I will be purchasing the Victron 12/18 Orion smart converter soon. Please make any comments about this post or your experiences that you have. I intend to solve this problem. My fishing comfort and safety depend on it!

Patrick it seems to me that the issue is not the starting function of your LFP battery - you did not identify any problems with it handling the surge current of starting your outboard. The issues you describe are all on the charging side of the equation, and it sounds like your alternator is delivering too high a voltage for too long. The BMS (which is really just a switch that does not regulate voltage) shuts down charging when the cells are full, and your alternator is suffering no-load voltage spikes that will kill it. That is what you saw with the voltage bouncing between 14-18v. IMO you need to know how your stock alternator is regulated and, if possible, adjust that regulation to suit the LFP charging profile. Or replace the stock regulator with one that will support LFP - a likely more expensive option than the DC-DC charger.
Speaking of which - I believe that your alternator output is connected to the same main battery cable that the starting current flows through, right? If so then you may already know that a DC-DC charger will not help you unless you separate the alternator output from the main cable. The starting current cannot pass through the DC-DC converter.
You should have a good schematic of your motor's electrical system before you start this project so that you don't inadvertently cause other issues with its 'brain' while making changes to support your new charging setup.

 

[patrickparrott]

I agree with you on all counts Mark. The problem for me is how do I fix it when the Alternator is in an outboard motor and the boat wiring is what I would call primitive. It would be nice if I could just purchase a smart alternator or change the boat's wiring. I am going to try to get those schematics from the dealer who I have a good rapport with. What is interesting to me is that Dakota feels that they have a solution and have replaced one of my batteries with a different BMS upper shutdown limit that they claim will be ok with charging from the outboard alternator. It arrives today and I will install it tomorrow. They have been pretty successful with the bass boat crowd. I'll try to prove their solution soon with a tryout using only that battery. Also interesting is that the diodes in the alternator have not died yet. I think that Yamaha may have changed them to a very high voltage diode to keep them from being damaged. Thanks for your suggestions. I will proceed very cautiously!

 

[patrickparrott]

That you see voltage bounce around between 14-18 volts is concerning. That actually sounds like the battery had already gone into protection. If the battery had not gone into protection, then the voltage would not fluctuate, but would sit at the voltage of the battery. In protection, the battery would still power everything, just not accept any further charge, so you might not otherwise notice anything wrong. The fluctuation to 18V would happen as the alternator is generating power with nowhere for it to go.

What voltage does the alternator charge to when connected to a lead-acid battery? What voltage is the LFP battery when it is fully charged with an LFP AC charger? I don't know what the HVC voltage for the Dakota battery is, but it is probably about 14.6V. You would need to find a way to limit the voltage from the alternator to less than this. Typical for an inboard alternator would be around 14.4V, and thus should work just as a drop in. If adjustable, the ideal voltage is around 13.8V. I have no idea what voltage an outboard alternator charges at.

What is the max current output of your alternator? You will not get a large load dump voltage spike unless there is a lot of current flowing at the time it happens. A small alternator isn't going to create a large voltage spike, and neither will there be one if the battery is fully charged when it disconnects, because current into a fully charged battery is low. The 18V might actually be a load dump from the battery disconnecting. That is small enough, I doubt the Balmar APD would even attempt to squash it.

Your theory seems correct. Because the current is low at low rpm t it doesn't cause a shutdown, only erratic behavior. The erratic voltage is happening at very low engine rpm, just above idle. When the battery goes into protection and shuts down the motor is at a much higher rpm. I only get the shutdown at high rpm when I suspect the alternator current is high. The voltage spike is caused by the current dumping. I'm trying to find a way to limit that voltage and change the shutdown limit on the BMS. Dakota sent me a new battery with a higher shutdown limit but that doesn't do anything for the alternator issue. Just a band aid. Probably need both. I need to regulate that current better. Maybe that's why they are suggesting the Victron Orion. I've asked them for a wiring schematic when using the Orion with two lithium starter batteries, but they haven't responded yet. I'll install the new battery tomorrow and see what happens when only using the new battery. Proceeding cautiously and feeling like a Guinee pig.