RV Repair: charger/inverter, fuse box, harbor freight

Question
I have 96 newmar mountain air with a power source 75 (pc75)it seems to be working but does not charge the battery and they seem to lose the charge,as if there is drain when nothing is turned on,how do I find the drain and find what is not hooked up right? or the proper way it should be as it also drains the engine battery too. hope that you can give me some insight on this thanks. Brian

Answer
a short that is related to both batteries.  what systems on your Rv is related to both systems?  If you had a DVOM, Harbor Freight, you can check for amp draw.  should be none.  If you see amp draw, start turning off breakers until the draw goes away.  If not in the Rv, then start pulling fuses from the fuse box for the drive train.