Poor House Battery Connection
We just got back from a great six week trip in our 2006 View. After a couple of travel days I noticed the house batteries were not fully charged. It turned out to be a poor connection of the negative battery conductor to the Sprinter frame. The connection was made with a self tapping 3/8 bolt through the frame. The bolt installation caused a ridge to form around the bolt hole and the ridge decreased the surface area of the conductor lug to frame connection. I filed the ridge off to get maximum surface contact between lug and frame and the voltage increased to normal after one travel day. I'm sure the age of the rig, corrosion and 50,000 miles had a lot to do with the problem, but it is a maintenance point worth checking. And something to check before replacing those house batteries.