Many MH have a problems with Parasitic drain.
My Class C chassis battery would go dead after a week or
two at home.
I found all kinds of monitors had been
added durning the build process. From O2, Gas, steps
you name it. All tied not to the house battery but
to the chassis battery.
I keep mine pluged in at home, with a batter mindeder pluged in
an inside 120V and then into the 12v power outlet on the dash.
For the past year + no dead batteries.
The link below may help.
http://www.flashoffroad.com/electrical/Batteries/BatteryDrain.html