The temp range of the Firefly 4v carbon foam cell appears to be -20c to 50c for "operation" and -30c to 60c for storage, which is 122F and 140F for the upper end respectively. I assume their group 31 battery will have the same temperature spec but have not found a similar data sheet. I got this off of the "download" link on this page:
Bruce Schwab's site had equated 50c to 104F and that's wrong, so other sites may be using those numbers.
Very possible, but even the low end of -20C for operation could make heaters required if it wasn't inside, as you wouldn't be able to get it that warm if in cold outside conditions.
I agree, the temp range is still limiting on the low end, but the high end looks better.
Still, the $550 100ah 12v group 31 might give me an option for the Toyota Sienna conversion I'm pondering if it doesn't outgas into the living space. It claims to be sealed fwiw.
I think that low temperature storage would be limited by freezing temperature of the sulfuric acid electrolyte in both AGMs and Carbon AGMs. Freezing temperature varies with concentrations of H2SO4 which varies with SOC. Fully charged batteries will have high acid concentration hence lowest temperature limit for storage.
Linear Mode
