No idea why the auto-reset breaker is tripping but I would inspect it regardless.
The auto-reset breakers are prone to corrosion if exposed to water, which they often are. Ours had very corroded connections because the TT was delivered to the dealer in the winter with lots of salt on the roads and I replaced it. In addition, when I went to do some wiring mods, the main positive wire from the battery fell clear out of the crimped ring terminal at the breaker because it was improperly crimped at the factory.
Use a voltmeter and see what the state of charge is like on the battery then you'll know if it's the battery itself or some other issue(s). Breakers trip when their rating is exceeded so if it is tripping, it's either faulty or there is an excessive current draw. Those breakers are pretty cheap. I have a spare in a drawer. What type of RV? A TT or FW could have one or more other auto-reset breakers and you could switch them around.
