If castle is listening think there needs to be a programming option where you can set your own auto detect voltage. e.g 12.8 volts if a 4s pack is detected and 16 volts if a 5s pack is detected, otherwise it would be PITA to have to reset the cuttoff every time you alternate between packs.
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy