Originally Posted by Wertles
I keep my coach plugged in all winter so that battery stays charged. I have a battery tender plugged in the coach and feeding into the 12V cigarette outlet to keep the chassis battery full. Best 24 dollars I ever spent. I don't need to remove either battery for storage and all I do is turn the key in the spring.
I do the same as Wertles. In a Ford E450, the dash 12v outlets are always on, so they are connected to the chassis battery. The Battery Tender works well and doesn't overcharge.