bkenobi wrote:
The batteries should have been maintained during transit at 2A.
From what source ?
IF the system really is designed to charge in transit, there usually is a solenoid that closes to charge the house batteries from the chassis alternator......but that would not be limited to 2 Amps.
Both of the used RVs I've bought recently had that solenoid bad. The last one called it a "battery isolator".
More tests are needed, including testing that "charging in transit" source that you think should be present.
P.S. The breaker tripping would tend to indicate that the converter/charger is drawing a REALLY high initial current, maybe indicating that the batteries are indeed weak.