I’ve spent the last three days trying to figure out why my coach couldn’t work on dc alone. I looked for a tripped breaker, especially the “manual breaker” mentioned in some posts but couldn’t find any on my 2010 Yellowstone class c. Fortunately I didn’t destroy my dc fuse panel, under the foot of the master bed, I found 3.7 v there. My batteries were reading fully charged (I have installed solar panels) and am plugged into shorepower most of the time. Eventually I decided I had to check the batteries instead of just reading the monitor. Each battery read 6.5 or so, but did not equal 12 across outside terminals. The jumper wire connecting the positive and negative terminals between my two 6v deep cycle batteries looked good and tested good for continuity. I used a temporary connection to replace the jumper and lo and behold I now have 13.7 volts and everything works including starting the generator. I could only start it for the last couple of weeks if I had the motorhome engine running. I didn’t know I didn’t have battery power because I was plugged Into shorepower so everything worked off the converter until I unplugged the cord and everything went dark! I also connected my charger to the batteries to test if they were good or needed charging. They were both fully charged so that narrowed it down for me. I cut the insulation off the old jumper, one end had a crush type blue plastic o ring connector, the other end had a plain o ring connector that had electricians tape wrapped around it. The wire was good, the issue was corrosion on the end with the plastic cover the wire inside the connector was all greenish copper corrosion, killing the continuity. I had expected the taped end to be bad but it was fine. Anyway, I have correct voltage and everything works again! Hope this helps somebody, especially if you’re using two 6v batteries. Another place to check!