The side and rear doors of the minivan are power assisted. After a couple days of camping, the starting battery is flat from door opening. Starting batteries provide cold cranking amps in a quick burst, not sustained loads. They aren’t designed to be run flat and recharged over and over.
So, I installed an Optima Yellowtop battery. It is designed as both a starting battery and a deep cycle battery. It has more reserve to handle more door opening and can deal with repeated discharge and recharge.
A WirthCo Battery Doctor battery isolator isolates the starting battery from the 160Ah house battery in the back of the van. The red 4 gauge wire runs the length of the car, connecting the starting battery to the house battery via the isolator.
The button marked PUSH is an override that allows charging the starting battery from the house battery. The starting battery must have some charge remaining for it to work. When my old starting battery ran flat from door opening, it was too discharged for the override to work. I’m curious how the override will behave with the new battery.