I just got a 1998 Bounder motorhome. Need help with the two battery switchs located just to the right of the door as you enter the motorhome. The panal is labled BATTERY DISCONNECT and on this panel are two switches. One is AUX and the other is MAIN. When do you use the AUX and where does the power come from? Also, when do you use the MAIN and where does the power come from for that switch?