Upgrading/replacing 12v SLA with LiFePO4

I'm wondering if it's possible to swap the SLA for a LiFe battery. Normally, it's just a drop-in replacement, no questions asked. However, EVs are a special case because the charge systems are much more sensitive, and the Leaf might be doing something much more advanced than a float charge on a typical ICE.

I'm not asking if it's cost effective or worth the weight savings. Just, if it comes down to it, when I need a new battery, should I buy a Li or another OEM-vetted SLA?

One of the reasons I'm interested in the Li is the capacity, and duty cycling. SLA loves to be at 95-100%, while Li batteries favor 20-80%. Based on how the Leaf handles recharging the accessories battery, it seems it never keeps it at 100%, which could reduce life expectancy of the SLA. Look around the forum, and you'll see more than a couple complaints about a drained or premature failure of the SLA.

And because it's very relevant, I have the '14 SL (with the solar panel), which actually helps keep the SLA nearer 100%.

Yes, it is possible as a drop-in but as you said it makes no economic or practical sense... I'm at 3 1/2 years and my battery is still in excellent shape... Were it to die, I'd go down to Costco, Pep Boys or Kragen and just get a new one...

Your reasoning about how the charge level is maintained is sound. While most people won't bother with the expense or adventure of a lithium-ion based battery, a few will. If you keep searching the forum, you will find an instance or two of this being done. As far as I know, there have been no complaints about the results.

Don't count on that solar panel charging your battery much. It can barely keep up with the parasitic drain of the electrical system, and that's after everything goes to sleep.

gbarry42 said:

Don't count on that solar panel charging your battery much. It can barely keep up with the parasitic drain of the electrical system, and that's after everything goes to sleep.

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I'm aware of the paltry output of that solar panel. I've joked about it with a few friends and colleagues, mentioning that after 10 years I'll have accumulated 1 full charge.

I can't find the specs on it, but I heard somewhere it's rated for 1.8W. Not even enough to power my phone…

TomT said:

Yes, it is possible as a drop-in but as you said it makes no economic or practical sense... I'm at 3 1/2 years and my battery is still in excellent shape... Were it to die, I'd go down to Costco, Pep Boys or Kragen and just get a new one...

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I hope my SLA lasts 3+ years. On my Accord, they generally last 18mo. It also takes a hell of a beating with my 2000W subs in the trunk…. My point was mostly if I had to spend ~$100 on a new battery, why not spend an extra $20 or so and get the Li variant?

I keep forgetting to check the specs (CCA/AH) on the 12v, but being a deep cycle SLA, I doubt the CCA is higher than 200, so a LiFePO4 could still output enough power to run everything.

gbarry42 said:

Your reasoning about how the charge level is maintained is sound. While most people won't bother with the expense or adventure of a lithium-ion based battery, a few will. If you keep searching the forum, you will find an instance or two of this being done. As far as I know, there have been no complaints about the results.

Don't count on that solar panel charging your battery much. It can barely keep up with the parasitic drain of the electrical system, and that's after everything goes to sleep.

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If I were to replace the 12V with a Lithium alternative, I'd disconnect the solar panel. Float charging is a lead-acid procedure that does not carry over to Lithium. Overcharging Lithium batteries is dangerous, regardless of how low the current is.

Nubo said:

If I were to replace the 12V with a Lithium alternative, I'd disconnect the solar panel. Float charging is a lead-acid procedure that does not carry over to Lithium. Overcharging Lithium batteries is dangerous, regardless of how low the current is.

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Any decent automotive replacement lithium "12V" battery is going to have a BMS that will prevent any issues with overcharging. If it doesn't - I wouldn't use it!

Nubo said:

If I were to replace the 12V with a Lithium alternative, I'd disconnect the solar panel. Float charging is a lead-acid procedure that does not carry over to Lithium. Overcharging Lithium batteries is dangerous, regardless of how low the current is.

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I don't think that will be an issue. Most of the Li- batteries have a PCB to prevent that. Otherwise, the 60A+ output from the alternator would cause a much bigger problem.

Still definitely a valid concern. I'd have to look at the schematics/designs of the PCB, and the solar panel. An alternator can output anywhere from 12V to 22V, and it's usually rectified and conditioned to a stable ~14.6V for floating the SLA. From my understanding, the Li- batteries designed for automotive use are designed to handle that 14.6V safely, even when at full capacity.

I have a LiFePO4 battery in my YZF-R06, and overcharging isn't an issue. I also don't have a solar panel on my motorcycle… but I don't think it should make a huge difference, as I've ridden for 150mi in a single stretch.