1984 - 26ft Class A GM Motorhome. I am having electrical issues with my motorhome. It seems that I can not get any of my electrical items to run off battery power except for the water pump. None of the lights work, the fan does not work, nothing. Even when the motorhome is running nothing works except for the pump. When I have the camper plugged in, everyhting works just fine. I have checked the fuses that I can find and they all seem to be OK. I really dont know what else to check. Can anyone give some suggestions on where to start? PS - The batteries are charged.