I have the chassis and house batteries connected together with a #14 wire installled by Ford’s auxiliary battery feature. I removed the relay, replacing it with a piece of wire. This works great for more than half the year when the solar panel keeps all three batteries topped up. In winter I disconnect all the batteries, checking every month to make sure they are close to fully charged. I also take a drive every month. Our climate is milder now with a thaw every month.
The MH battery does winter better than our old van that gets too many trips too short to top up the battery after starting. I disconnect the battery most of the time, watch closely and use a maintainer or charger to keep the battery over 12.3 volts.
