Great, long post with many pages of comments helping diagnosis electrical problem is here.
The below is a copy and paste of useful information, and I usually recommend it to those just starting out. Some of it, you may already know, or may not be applicable to your particular RV. You will be able to filter out what pertains to your situation or not. I would suggest you read the electric threads and energy management first, and then the converter thread. This will help explain your different electrical systems of your RV, and how they operate…as well as what the converter does. The very first link will explain what operates off what system.
Your very important converter:
12 volt DC:
Suburban water heater (if applicable to your RV):
Water Heater bypass/crossover valves:
And the newest additions to help understand what constitutes a true full cylinder in refilling vs exchanging propane cylinders… as well as how the automatic propane changeover regulator works:
Inverters and residential refrigerators in RV’s: