LiFePO4 Main Battery Replacement

[Wabujitsu]

I am considering the idea of replacing our Jeeps’ batteries with LiFePO4 batteries, when the AGMs wear out.

Has anyone done this? Will the stock alternators properly charge them? Anything I need to consider before doing this?

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[Nokones]

It will charge them, but not with the right charging algorithm that a Lithium battery requires. Lithium batteries require a special charging algorithm or the battery may be damaged and not perform well and have a short service life. Also, there is a high risk that the battery may catch fire.

 

[Wabujitsu]

It will charge them, but not with the right charging algorithm that a Lithium battery requires. Lithium batteries require a special charging algorithm or the battery may be damaged and not perform well and have a short service life. Also, there is a high risk that the battery may catch fire.

Kenny, thanks for your reply.

I keep reading in reviews that LiFePO4 batteries are LESS prone to catching fire than AGM batteries. Why do you say the opposite? Are you referring to improper charging causing a fire?

Also, doesn’t the onboard BMS contain the algorithm?

 

[Nokones]

Kenny, thanks for your reply.

I keep reading in reviews that LiFePO4 batteries are LESS prone to catching fire than AGM batteries. Why do you say the opposite? Are you referring to improper charging causing a fire?

Also, doesn’t the onboard BMS contain the algorithm?

They are less prone, but the wrong charger could cause something catastrophic to occur.

I am not sure what all the BMS does and doesn't do and it may protect the battery to some degree from the use of an improper charger. Besides the specific required charging algorithm, the Lithium battery does require a specific certain charging voltage rate that is different than a wet cell and an AGM battery. The AGM battery also requires a specific algorithm and charging voltage rate than the other battery chemistry types.

 

[Nokones]

I agree with above poster. I have been researching for a while switching to LiFePo and the genesis dual system. In order to properly charge and maintain a lithium battery, you must have a proper device like the Redarc DC-DC that comes with the Genesis system. Out of the box, charging lithium off your alternator and have the IBS control it is going to cause problems.

In case of the Genesis off-road setup you get to be able to have both types of batteries, mixed, if wanted. Genesis recommends the LiFePo for accessories only and not as the main, where they continue to recommend an AGM. Though there are specific “starter version” LiFePo’s, it is seemingly still a bit of a lesser application for them.

EDIT: I believe the issue is, aside from voltage differences, that the IBS tries to never charge the battery fully. In the Genesis setup I think the IBS is deleted fully along the Aux battery.

Genesis definitely knows there stuff I fully trust Genesis and there products.

 

[nU7OuxIx]

I've read over the years that lead-acid/agm batteries are better for that peak shock electrical load whereas lifepo4's are better for steadier, more even loads. I can't scientifically explain it but it makes sense.

Lifepo4 also aren't great in cold weather. I want to say around 32* is where their voltage drops and you need to warm them before charging.

 

[Tr4ckD4ys]

I've read over the years that lead-acid/agm batteries are better for that peak shock electrical load whereas lifepo4's are better for steadier, more even loads. I can't scientifically explain it but it makes sense.

Lifepo4 also aren't great in cold weather. I want to say around 32* is where their voltage drops and you need to warm them before charging.

All true. A good LiFePo costs 800$+ and comes with an internal battery management system with Bluetooth connectivity, to prevent overheating and other issues. They also sometimes have “warming” mechanisms in them. 1000$+ for something like that. Add in the Genesis system and you’re out almost $3k for a dual battery LiFePo system.

 

[Wabujitsu]

All true. A good LiFePo costs 800$+ and comes with an internal battery management system with Bluetooth connectivity, to prevent overheating and other issues. They also sometimes have “warming” mechanisms in them. 1000$+ for something like that. Add in the Genesis system and you’re out almost $3k for a dual battery LiFePo system.

Surprisingly, you can get a Bluetooth battery with heater, designed as a vehicle start battery, for $369: https://lithiumhub.com/product/ioni...WgMv2mdA6zpCnfn4IF1K1_g3Zgn_ooXnMWHBtb5W58pbc

 

[Tr4ckD4ys]

Surprisingly, you can get a Bluetooth battery with heater, designed as a vehicle start battery, for $369: https://lithiumhub.com/product/ioni...WgMv2mdA6zpCnfn4IF1K1_g3Zgn_ooXnMWHBtb5W58pbc

Yes - I was mainly looking at the American-made brands like Dakota Lithium

 

[Nokones]

I've read over the years that lead-acid/agm batteries are better for that peak shock electrical load whereas lifepo4's are better for steadier, more even loads. I can't scientifically explain it but it makes sense.

Lifepo4 also aren't great in cold weather. I want to say around 32* is where their voltage drops and you need to warm them before charging.

My 23 Wrangler Rubi has the 48 Volt LifePo4 battery in the back and must be the reason why they have cooling lines going back to that battery to keep it cool in the summer and warm in the winter.

 

[Nokones]

All true. A good LiFePo costs 800$+ and comes with an internal battery management system with Bluetooth connectivity, to prevent overheating and other issues. They also sometimes have “warming” mechanisms in them. 1000$+ for something like that. Add in the Genesis system and you’re out almost $3k for a dual battery LiFePo system.

The LifePo4 battery I had installed in my Golf Car to replace the six 8 volt wet acid batteries and save 300 pounds in weight cost $2800 with labor.

 

[Ratbert]

Why?

They're not designed with the characteristics desired for starting the engine, they're extremely expensive, and you have to make damn sure to never charge them below freezing.

If you were powering a camper or something similar, then absolutely, it'd make sense for the additional amp hours, longevity, and weight reduction.

Here it's a shitload of money for not a lot of benefit.

If you're looking for more amp hours then consider a @Genesis Offroad system. Significantly less headache.

 

[Spartywarrior]

I am considering the idea of replacing our Jeeps’ batteries with LiFePO4 batteries, when the AGMs wear out.

Has anyone done this? Will the stock alternators properly charge them? Anything I need to consider before doing this?

Never had a problem with my Antigravity battery. Solid battery.

 

[VKSheridan]

I wouldn’t do it. The reasons are many but here’s my Top 3

1) LifePo4 is fantastic for low and slow discharge. Unlike an AGM battery, most LifePo4 batteries are not designed for hard bursts of cold cranking amps. Maximum amperage discharge as well as recharge is controlled by the onboard BMS. BMS is not a regulator that limits amperage flow, it’s more like an on/off switch that stops flow altogether until it resets.

2) LifePo4 doesn’t like the cold. The chemistry within the cells allows discharge in temperatures as low as -4F but the cells cannot accept a charge below 32F. With this in mind, the onboard BMS will electronically disconnect the battery from the circuit to protect it. When disconnected, you will have zero volts to power the memory in your radio much less turn your starter. Jumpstarting will not make your battery work, warming it is what it will require.

3) LifePo4 isn’t a huge fan of the heat. The chemistry of the cells is optimal between 60F and 104F but lithium really, really, really likes to shed electrons which risks thermal runaway if the cells are exposed to too much heat. Most BMS will trip and electronically disconnect at around 140F. 140F under the hood is extremely easy to achieve, especially in traffic.

We‘re running a pair of 400 Ah LifePo4 batteries in our Class A RV for a combined output of 10,240 watts to power it when we’re off the grid. Our lithium batteries can recharge at up to 200 amps per hour, they weigh less than the 4 AGM batteries they replaced and they can discharge well past 50% without risk of damage. No gassing, no corrosion, no worries of explosion around sparks. In that application, I think they make lead acid filled batteries as obsolete as a postage stamp. To start our RV though, we’re sticking with the AGM battery.

As a footnote, the alternator in our RV is used to not only charge our AGM starter battery but our Lithium batteries as well. The alternator doesn’t care if it’s connected to 12 VDC lithiums or 12 VDC AGM cells. Output is regulated by the voltage regulator, not the battery. The only “drawback” is when the alternator drops to a float phase of 13.5 VDC, the lithium cells don’t really want or need it if they’re fully charged. No harm or damage, just potential fuel burned to make energy not needed.

Lithium requires less absorption time and no float time which is why it’s best to use a lithium capable charger as a maintainer instead of an old school battery charger.

Said differently, Lithium needs just two phases of charging - Bulk and absorption since there’s no sulfation to worry about whereas AGM chargers are built to provide 9+ stages.

Can you use a conventional charger on LifePo4? Yes but because the charger will decrease voltage by design to prevent potential sulfation, it’s unlikely the battery will get fully charged. It won’t hurt it, you just won’t get the full capacity that you paid for.

Cheers

 

[Ratbert]

2) LifePo4 doesn’t like the cold. The chemistry within the cells allows discharge in temperatures as low as -4F but the cells cannot accept a charge below 32F. With this in mind, the onboard BMS will electronically disconnect the battery from the circuit to protect it. When disconnected, you will have zero volts to power the memory in your radio much less turn your starter. Jumpstarting will not make your battery work, warming it is what it will require.

A decent BMS will simply disable charging when below freezing, not discharge.

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