The "salesman switch" on my coach is distinct from the Battery Disconnect. The disconnect switch is located in the house battery compartment and cuts off most of the current from the batteries. If the inverter is left on there will be some draw for the autogen start etc. The Salesman Switch is by the entry door and, operating through a relay, it cuts off 12 v DC to the interior of the coach, lights, refrigerator etc. I can see no use for it since it turns off the refrigerator. If it didn't do that, I would consider it a neat master light light switch. As it is, as a full timer I never have a use for it. Also I have adequate solar that I can leave the coach stored outdoors and only need to cut off the chassis batteries as the solar keeps the house up just fine.