Now that we have added solar , I leave all three battery switches on. Our rig is parked in the backyard and gets daily attention to the little things of maintenance.If yours is like most of the mh’s I’ve had leave the battery switch on when using the thing. The switch, sometimes referred to as a “Salesman” switch is there to keep the house batteries from draining while sitting on the lot or otherwise not in use. The switch, if off, may prevent the house batteries from charging on shore power.