I have no 12 volt power in my 2009 Gulfstream Kingsport 380 FRS. At first the shore power would not keep the battery charged. Only charging the battery with a charger would keep the 12 volt system working. After a while the 12 volt would shut off and after a few minutes would come back on. Eventually the 12 volt system shut off and would not come back on. I checked the battery with 3 different chargers and a volt meter and all said it had a full charge. I checked the 50 amp fuse and the 15 amp fuse at the battery box and those were fine. I then bypassed the fuses with a charger and still nothing. what would be the next steps? Does this sound like a converter problem or a problem or the circuit board?
if the converter is working then the battery will show 13.6 volts across the terminals.
there should be a 110v fuse dedicated to your converter in the distribution panel.
switch that off and then read your batteries. I'd expect them to be shot.