A guy asked about hooking up a 24 volt light on his boat. He has 3 batteries , (1 for starting , 1 trolling battery, 1 for accessories). Everything is 12 volt but why can't he put a jumper (neg to pos) between two batteries, hook only a postive wire to one and neg wire to other for 24 volt and still hook rest up normally for 12 volt ? This cause any problems ?

