12V A123 LiFePO4 w/ BMS car battery replacement?

[wb9k]

In general, I agree that a Li drop-in replacement for a typical LA starter battery doesn't make sense at this point. Times are changing though.

 

[TwoWayStreet]

I understand the general reasons why lithium may be advantageous, I was more curious why the OP wanted it. I've done the math and I can buy a lead starter battery warranted up to 6 years for $70 at Farm and Fleet, makes spending several times as much on a not-quite-mature technology seem less appealing even despite the long life and weight savings. Not suggesting it's a bad idea, but in general I don't think lithium batteries are yet a better option than lead for starter batteries unless there are other factors. I plan on putting one in my boat to run accessories when the motor is turned off, but I still wouldn't use it for the starter for various reasons.

Economically, it does not make sense. I have found only one case that makes LiFePO4 a good choice for starter batteries. I have 4 motorcycles. They are not for transportation. Just toys. There are times that I don't touch 2 or 3 or them for up to 8 months. So I had to keep the lead-acid batteries charged, and it's a pain in the neck for me. With Lithium, that's no longer an issue. So now each them gets a 4s2p A123 26650 battery.

 

[dmwahl]

Economically, it does not make sense. I have found only one case that makes LiFePO4 a good choice for starter batteries. I have 4 motorcycles. They are not for transportation. Just toys. There are times that I don't touch 2 or 3 or them for up to 8 months. So I had to keep the lead-acid batteries charged, and it's a pain in the neck for me. With Lithium, that's no longer an issue. So now each them gets a 4s2p A123 26650 battery.

That makes a lot of sense, motorcycle batteries seem to wear out much quicker than car batteries and they cost almost the same. The weight savings would be more noticeable as well.