Electrical mystery

On two occasions already the Revcon has totally gotten drained out of all three batteries. First time happened right after we got it home, and today we noticed that it has happened again. First clue was that the stairs did not retract out when we opened the door, also the automatic locks did not work. There was no charge left what so ever. Our neighbor, super handy guy, who knows everything about plumbing, electrics or building anything (I bet if asked, he could build a space craft, we... not so much) took a look of it with Lee. They went through all the wires, and they seemed to be working just fine, but for some reason the batteries just get drained out.

See the cord running to the Revcon... hope it gets a bit charge from that.

We are suspecting the fridge, since it should not be on at all, but today even after quite cool night, the freezer felt really cold, colder than what I think it has been at any point in the last month. Lee suspects that there is some sort of limping mode that it goes into in some events and will stay there until the batteries are drained. I know nothing about limping modes, or anything else electrical, I just hope that we get it resolved before hitting the road, would be really sucky if we got stuck somewhere cause our batteries unexpectedly died. Limping doesn't help, the food will get spoiled anyhow after the limping ends in few hours, but the trip is spoiled long before that if you are stranded in the middle of the wilderness. Gave us something to think about. Have to come up with some sort of emergency plan for the cases like that.

What is going on here???

We are scratching our heads, me mostly, cause I'm not really good for anything constructive with these matters. Though I have made plans of painting some, and changing the flooring and other grand ideas that will not help at all. But hey, someone has to be the one who thinks about pretty things. :D
Any ideas are welcome! I know that solving this distantly is pretty impossible, but maybe experience will give some possible clues to what might cause this.