I just had a similar problem with my Jayco Greyhawk. We are getting ready for a Florida trip. I had the unit hooked up to shore power in my drive. When I went to start up for a shakedown drive, there was no power to start the engine. Used the "emergency" button and the coach batteries started the engine fine. I took it to the dealer and explained my problem. I was told that the chassis battery only charges when the alternator is working i.e. when the engine is running. They said that I needed to put a trickle charger on the chassis battery when I shut down for a month or so.