I can concur with the same experience that both the Liberty and Marathon owners have had. The Watchdog on our Liberty was a source of periodic frustration which we had fixed on several occasions. I ended up writing some of its performance off on the age of the 1994 coach technology. Bottom line on that bus was that Autostart did work if you left the coach unattended for a significant period of time. Yet while we were in the coach I tended to run the genset to coordinate with our power usage and sleep schedule. AC would not run unless on shore or generator power anyway so battery life was as much as 12 or more hours merely running refrigerator and a few lights.
Currently I let the Marathon kind of do its own thing unless we are camping where there are specified hours for generator use. Batteries will run AC up to 2 AC units somewhere from 2 to 8 hours much like Jerry stated. My batteries are 2 years old and I am starting to see a very slight decrease in stored capacity. This thread has got me thinking about set points but in my past discussions with Marathon they have been pretty confident with their stock settings. I am open to any comments which would increase their lifespan....
Towson Engsberg
2006 Legendary XLii DS