I’ve made a few posts about using the Sears DieHard 1150 as a “house battery” system in your minivan RV.
These units have a built-in battery with charger, a 400 Watt 120v inverter, and USB power supply, for not much money. But how much power can they really provide? To find out, I staged a very unscientific endurance test, but we still learned a couple things about how to get the most out of a limited power source. Check out the YouTube video to see what we discovered.
You can find all of my technical and minivan camper conversion DIYs, linked here.