John Wayne wrote:
On most MH (gas) the starting batt. is only charged when the engine is running. The starting batt. powers among other things, starter , steps,back up camera, some cigarette lighter ports, hard wired smoke and propane alarms, etc. you need to look into a Trik-L-Start unit to keep the starting charged while hooked to shore power.
On our DP the chassis battery also powers the hydraulic pump motor for the stabilisers and slides.
Even so, three days is a very short time to go completely dead. There is something wrong somewhere. Something is drawing current continuously.
Once you diagnose and repair the problem, some sort of chassis battery charger is recommended. We use the Xantrex Echo Charger.