I currently have this setup in my van:

Alternator -> Car Battery -> Voltage Sensitive Relay -> Leisure Battery (AGM)

I'm thinking of changing out my AGM battery with a LiFePO4 battery instead, which I know has a very different charging profile to an AGM and also has a low internal resistance compared to an AGM. Can this be problematic?


  • 1
    If you consider fires and explosions to be "problematic", then yes it can be problematic.
    – Elliot Alderson
    May 21 '21 at 15:07

Yes it will be problematic.

A LiFePO4 battery charged by a car alternator regulator will most likely fry the alternator. The sustained low resistance of the battery will pull a high current from the alternator and it will overheat.

If the alternator does not fry you will most likely wreck the battery. LiFePO4 batteries are easy to charge however they have a set of charging requirements that are not met by a system intended to charge lead acid batteries. In particular sustained overcharge or float charge will very quickly degrade the battery.

You would need a charging system designed to charge LiFePO4 and then a method of topping up your start battery, a battery to battery charger is a good idea here. This would mean changing or modifying your alternator and installing an external charge controller.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy