Hi,
I guess this device likely uses a 1mOhm Rds(on) nfet with a gate driver since it can operate as a low side or high side switch, controlled by a microcontroller.
It has a 10ms rated current of 2400A. It would be cool if the under voltage cutoff could be adjustable, ie this device could be useful to use for a supercapacitor hybrid battery potentially and not just lead acid batteries.
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It seems a bit risky putting a switch in series with the battery, if that device failed in the open state while driving that could disconnect the battery and cause problems with the car's electronics etc.
cheers, Jamie