Its a standard (Walmart) marine deep cycle battery, I'm thinking its a group 27. One battery for coach and one for the truck.
I can also tie the truck battery into the coach circuit so the truck battery can also stay charged when on shore or gen power.
I did this upgrade in my ole Toyota, mainly to keep from cooking the battery but also to gain the quick charge capability of the three stage converter.
2001 Coachmen Mirada (Ford F53 6.8L V10) - Toad 2003 Saturn Vue.
It won't do MACH 2, but I can get a sandwich and take a pee.