i have a 1997 nitro boat. It has 3 batteries, one for the engine and two for the trooling motor, however the two for the trolling motor are NOT connected togther that i can tell. The trolling motor has a 4 prong plug end taht says 12-24 volt. Also the red leads of the two batteries have connetors that allow these batteries to be diconneted (unplugged) by simply pulling the wires apart. Also the trolling motor is set to 24 volts which is the way it was when i bought it used. Do i have a 12 volt system, 24 volt system ad how should i charge these batteries?