I've got a 1979 Komfort travel trailer. I've got a new battery and keep it fully charged with a 60W solar charging kit. All the 12V power will be on fine and all of a sudden it goes out to the furnace fan, lights, water pump. However the 12V outlet(cig lighter) is still on. If I plug in the 120V panel through the converter I've got no problems and everything works through out the night. Could it be the thermal overload switch at the front of the trailer by the battery? If so does the cig lighter inside not go through that?