Our '16 Tif 36la has a Res refer, with a 2000 w inverter and 4x 6 v batteries. When we get to a spot, and the batteries are charged, I usually don't need to run the Genny until the next day, and then about 3 hours to recharge. But that is based on other demands which we might have on electric. Of course, if the fans are running, the water pump , lights, or tv. Then more.
We got in the habit of not opening the refer door much at night, and have a small cooler for beers or soda. Also, if equipped, turn the ice maker off! Good luck!
Denny, Rosie and Josie the Beagle
2016 Allegro 36 LA
2016 Mazda 3