Those FETs say they’ll do 70A continuous each, with case temp at 100C. Maybe I’m missing something thermally (that the aluminium block heat soaks really quickly and then can’t dissipate it) but from the datasheets it seems fine for a lot more than 20A? I can’t quite read the part numbers on all of the fets to confirm if they’re all the same and ganged up in parallel, maybe they’re laid out in a way that severely limits it like one series FET needing to take the full battery current, but still it seems reasonable
@ApproachCautiously I think you should put down strips of fish paper between the overlapping balance wires, that’s the standard method like these from Al. The little rafts keep them safe from eachother