Hi there, IÂ´ve a problem with the coach battery. The battery will be charged only when the generator is running or when the RV is pluged in at a campground, not when the engine is running. There is a big black electronic box under the front hood, left side. In the box is a kind of relay or solenoid, Master Electronic Control, NI-4412. Does anybody know if this solenoid is responsible for charging the coach battery, when the battery for the engine is full enough?