[Riwright]

Search for threads that have to do with running the refrigerator while driving. A lot of people see the frig in DC mode running down the battery because the amount of current that makes it from the tow vehicle to the camper is too small. Sounds like you have a similar problem.

Usually there is a voltage drop between the tow vehicle and the battery. The wiring runs can get quite long. Installing heavier gauge cable will usually help.

I recommend the yearly membership. If you own a Trailmanor there is a lot of good information here.