My first MH was '97 Suncruiser. The batteries were under the steps. The engine start battery is connected in a conventional manner just like a car. The two house batteries are connected in parallel to produce 12v. I was able to just barely fit 4 deep cycle 6volt batteries in the footprint of the two 12volt house batteries. That improved my amp hour capacity for the same space. If any of this is "greek" to you get help so you don't damage anything.
George R. - Fulltiming since January '03
2007 Newmar Mountain Aire 3991
2012 Chevy Malibu LT1