truancy143

Don't mean to thread highjack but there's lots of useful information here.
Looking to replace my battery soon and am considering the following:

https://www.batterystuff.com/batteri...tx20ch-fp.html
or
https://www.batterystuff.com/batteries/ss51913.html

They're both LiFePo4, 507/552 CCA respectively.
I have a sound system. Amp, component speakers in doors, speakers behind the seat & sub woofer. Should I just stick with lead acid or is this a bad idea?

DefSport

The problem with LiFePO4 batteries for a daily driven car with lots of accessories isn't really the cranking amps. You only need maybe 2-3 Ahr of Li batteries to turn over a 4 cylinder. It's that most readily available batteries do only have these few Ahr of capacity. So sure, with enough charge it'll kick the engine over no problem, but the battery can now only take ~1/5-1/4th the steady state current draw when the car is dead.


This whole issue of marketing Pb Ahr-equivalent ratings just makes it even harder to compare apples vs. apples. Where they're trying to say that the lithium battery can still turn over the car even with say 25% charge, whereas a lead acid battery will not, so they multiply it by some arbitrary number like 4 or 5. That's not how batteries work at all though, so your parasitic draw will kill one in short order without religiously disconnecting it.



My personal take on the ultimate in lightweight battery tech for a daily driven car with accessories is a lighter lead acid battery and a bank of ultracapacitors to handle most the heavy lifting of starting. So you've got an honest say 10 Ahr of draw for leaving the car idle for a long period of time, and can legitimately start the car up with ~25-30% battery capacity remaining.


But really, the stock battery on an S2000 is ~25 lbs, so you're not going to save much weight (maybe 10 lbs for a legit SLA + ultracap combo that is pretty "foolproof"). A 2-3 lb lithium battery will probably leave you stranded for an occasionally driven car, and they do not handle high charging amps. I made that mistake with my first LiFePO4 battery pack. It was 9.2 Ahr, which is pretty big capacity, but I let it draw down over a couple of weeks and it did crank the car, but the high charging current killed a few cells and it was impossible to revive it.

manystyles

Because of this thread, I took the time to charge the battery and then drove the car normally. I no longer daily the S so I'll be installing a battery terminal switch.