[JRTJH]

It sounds like one of the mini-breakers (there's two) that are wired next to the battery. On travel trailers, usually on the A frame bulkhead and on fifth wheels, mounted next to the battery. It may not be the "actual mini-breaker" it may be a crimp on one of the ring terminals attached to it. But the symptoms look like it's in the electrical distribution "at the battery wiring"....