If there are any electrical engineering folks out there that are familiar with solar systems and custom built batteries, I could use some advice.

I'm running into an issue of having difficulty sourcing a 16s BMS for a LiFePO4 battery bank that includes a feature to cut off battery charging when the battery is below freezing.

I'm trying to figure out whether 2x 8s BMS with temperature cutoff in series would work, or whether I should just use the 16s BMS that I can find and figure out a solution to heat the batteries if they go below freezing.

@Anarkat There’s some risk when one BMS is shut down but the other isn’t - which is virtually guaranteed for at least a short period of time during any transition - but if you could find a way to AND their enable signals together you’d be pretty safe. Up to you which approach seems easier but I’d suggest rigging up your own temperature monitor, it seems easier and less prone to error, and lets you treat your subcomponents as black boxes which will be more pleasant to reason about.

@Anarkat that said I never finished the EE degree so I’m really not that much better than a hobbyist so you might want better advice than I have to give before risking expensive components

@solterrasa I'm fairly certain that the way things are going to be connected together, nothing will work if the system drops to 24-30 volts as would be the case if one of the BMS units turned off.

@emsenn @Anarkat I don't myself, but I enjoy reading about it!

And I know does, and here's a relevalent blog:

@Anarkat if 2 BMS in series and either one shuts down your whole pack is dead. open circuit, not half voltage, 0 volts, 0 current,.

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