[TennTom]

First let's get the terminology right. An inverter takes DC power and converts it to AC. A converter takes AC power and converts it to DC. With that being said your inverter won't have anything to do with charging your battery. I have not torn into my rig much but I do believe that in the front storage compartment on the left hand side looking to the rear at the felt/carpet covered wall there is a section you can take out. I would think that the converter is located there. Go in with a flashlight and you should be able to see the seam and the four blackfaced screws in each corner of the panel.
Hope this helps. Maybe someone else with a 381 may know.