Dead Chassis Battery

Picked up our 2014 Thor Ace 30.1 motorhome from storage yesterday and the chassis battery was completely dead. I just started it two months ago and let it run for over an hour and everything was fine then. I'm not sure why it went dead but my question is, I know when you have it plugged into shore power it charges the house batteries but does it also charge the chassis battery? I have looked and read in the owners manual but its doesn't really say. I know when the engine is running it charges both but I'm not sure about shore power. I can call Thor on Monday and find out but I thought maybe someone on here might know. If not I need to put the chassis battery on a separate charger.. Thanks Roy