FIrst there are two ways a RV is wired and one of those has an "A/B" option as well though B is very very very very rare in modern right
1(A/B)
Battery--fuse/breaer--Swtch--Everything else including the converter
2: Converter--Fuse--Battery--Fuse/breaker--Switch--Everything else
The A/B is some (one very old) converter insists you have a battery.
Option 2 is most common with Inverter/Chargers of 1kw or more (IE mine is a 2kw, but I have both 1 and 2 in my RV. Long story, aftermarket inverter).
How to test.
I like to use a TEST LIGHT this looks like an Ice pick with a wire coming out of the clear handle and a light bulb inside. Any Auto Parts place or department. I have several. I even make them up myself as needed.
Start at the battery.. Clip to NEGATIVE tip to Positive bright light good. No light re-seat the lamp in the handle and re-test Still no light test a known good battery (Your car) bright light on car.. Dead battery on RV.
NOTE at any point a DIM light is not good either)
Move clip to any unpainted frame thing IE: a bolt I've used brake lines and such as well. tip to Positive>> Still bright.. move out along the POSITIVE wire. find teh other end of it. Still bright at the other end (I had one case where the WIRE was the problem) move to the other terminal on whatever it is connected to (Fue or breaker normally at this point) still bright.. Keep moving.
Problem exists between Bright and not bright.
