I suggest that you check the inverter switch on the control panel of your Roadtrek Ranger RT. Mine was upside down.
I found it when I tried my TV, when not hooked up to AC or shore power. I turned the inverter on and tried the TV with out any luck. After trouble shooting the problem, I found out none of the lights were on. The inverter was completely dead. I found that with the switch in the off position it lite up and the TV worked.
The switch is just the opposite of all the other switches.
Also it works with the battery main switch off.
Now I see why the house battery always discharged.
The inverter switch was being left on, when I thought it was off.