Lithium battery house battery charging/alternator overload?

[T.R. Bauer]

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Anyway, generally speaking, LIFEPO4 batteries are not starting batteries as the others have noted. Keep your new battery and use it for a house battery only. It's proper to isolate it from the FLA batteries because it will bleed its voltage into your starting battery and vise versa without any way of knowing or control....not great. I charge mine at home, but can switch the house to a starting battery if needed.

Couldn't you put a diode between the house (FLA) and the Li battery? Current could then only flow into the Li battery from the house batt, but not the other way around.

Of course. Is there even an FLA involved though? I'm not really sure. I suspect Bob is right about the voltage drop issue though. There isn't much voltage drop, but there isn't much voltage to play with in 12v systems.