If you have 110volt "shore power" available where you store the rig, you might want to install a Trik-L-Start device that will keep the house batteries plus your engine starting battery fully charged. Most rigs have no provision for keeping the starting battery charged when connected to shore power.
Clarification: The Trik-L-Start device actually steals a little charging current from from the converter/charger and the house batteries and feeds it to the starting battery when you are connected to shore power.