My solar battery bank gave up at 3am during a heat wave

I run a tiny off-grid setup for my camper, mostly to keep a fan and phone charger going. Last Tuesday the temp hit 97 in Phoenix and my 200Ah battery bank just quit, no warning, no error code, just dead. I woke up sweating at 3am with the fan dead and my phone at 12%, the inverter was beeping like a sad robot. I spent an hour in the dark with a headlamp checking every connection and fuse, turns out the BMS (battery management system) fried itself, probably from the heat plus the load. I ended up running an extension cord from my truck's 12V outlet to charge my phone and a little USB fan for the rest of the night. The replacement BMS cost me $85 and took 4 days to ship, which felt like forever in that heat. Has anyone else had a battery system just die on them in extreme temps, and did you find a way to prevent it? I'm thinking about adding a thermal cutoff or just some foam insulation around the battery box for next summer.

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pipergonzalez14d ago

Phoenix in July is basically a test lab for stuff failing, so honestly, you got off lucky with just an $85 fix. Foam insulation is the last thing you want, it just traps the heat and cooks the BMS even faster, you need airflow and shade, not a blanket. Your truck battery trick worked, but next time just pre-charge a power bank during the day and leave the big system off until after sunset.