Two weeks ago, while plugged into 120V at a campsite, our 2012 16' Deluxe totally lost power and went into total darkness.  This lasted for a minute or two before lights came back on.  My initial expectation was that the campground lost power, coupled with our 12V battery either already being dead (due to charging failure) or cut off due to a blown fuse.  But we just couldn't figure out what happened.  No circuitbreakers had tripped, no fuses had blown, and the 12V battery was fully charged.  (We travel with a voltmeter thanks to a problem with the towing harness that occurred in 2018.)  Does anyone have any ideas re what could have happened?