Battery switchs

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?


Senior Member
Re: Battery switchs

Generally a 'battery disconnect' is used when storing the unit. It controls a relay which disconnects most of the load from the batteries, so they don't discharge as fast. Nowadays, they are not a complete disconnect, because modern units have dozens of computers in them which get upset if they lose all power.

Probably one of those switches is for the chassis (starting) battery and one is for the house (living quarters) battery bank. But which is which, I don't know.


Senior Member
Re: Battery switchs

Rick57, Welcome to the forum. The aux battery switch is strictly for the aux batteries. Those run the 12 volt stuff inside your coach, like lights, water heater and furnace ignitors, etc. The main is for the coach battery that is used to start your engine. If you have turned off the aux switch, you won't have any 12 volt power inside the coach and your charger will probably not charge the coach batteries when your on 120 volt shore power. If your main is off, you can't start the engine. Make sure your coach/aux batteries are in good shape. ;)


Senior Member
Re: Battery switchs

Or in other words, the "main" is the chassis battery or batteries and the "aux" is for the coach battery or batteries.