If by coach battery you are referring to the house battery (powers the living quarters). Then the common denominator is your converter charger is not working and possibly needs to be replaced.
First though I would find the circuit breaker panel and look for a tripped breaker for the converter. A tripped breaker will usually look like it's not in line with the other breakers. Once you find the breaker just flip it all the way off by pressing firmly in the off direction. Then flip the breaker back on and see if it starts charging.