Unfortunately we will need some more information, like how many batteries, brand etc. Otherwise a member with the exact same year and type of motorhome will be the only one who can answer.
In addition, how long the batteries last heavily depend on what is using 12V while on battery power. Sitting in the dark without any furnace, fridge, or hot water will make your batteries last really long compared to having all the 12V loads turned on fully.
In general, 2-12V or 4-6V will last about 12-24 hours depending on 12V usage.
With a bit more information we can help more.
Towr: 2007 Country Coach Allure 470 - 37 Sunset Bay Cummins 400 ISL
Toad: 2007 Jeep Grand Cherokee (yes, it has a Hemi)