I'm having occasional 12v power shut downs, usually after a few of us have had showers this happens (I guess a good stretch of power demand) . The entire 12V system shuts off for 2 up to about 20 minutes. The batteries have had a full charge prior to this happening and when everything kicks back on the batteries are showing a full charge. Is it there something in the converter that maybe heats up and as a safety backup it shuts things down?
Sounds like a self-resetting breaker doing it’s thing. However, under normal use conditions, which you describe, this should not occur. Something is amiss. You need to provide a lot more detail for some meaningful diagnostic assistance. Shore power (presumably not)? All equipment in use at time? Etc.
The self resetting thermal circuit breaker should reset in a maximum of a minute or two, and I agree with Scott - it should not be tripping under normal loads. If the entire trailer stays off for 20 minutes, something else is wrong. I'd check for a loose connection, possibly at the disconnect switch, battery, or the thermal breaker.