Voltage problems

Given that your voltages are all over the place with the generator running, I would go looking for a loose cable somewhere. My main concern is in the wiring of the batteries. I'm certainly no expert, but most RVs, I've found, use multiple 6VDC batteries wired to produce 12VDC. How did I find out this convenient fact? I, too, bought an older RV and replaced the 2 house batteries. When I did, I bought two brand new 12VDC marine deep cycle/starting batteries and wired them exactly the same way as the old batteries came out. Went inside to make sure I had current and when I flipped the light switch, the lights blinded me for about 5 seconds before they blew out. It then occurred to me that I had wired two 12VDC batteries in series, creating 24VDC....DOH! I blew several fuses in the 12 panel and had to replace the overhead 12VDC fluorescent fixtures and replace bulbs in the incandescent fixtures. Fortunately, I didn't burn out any critical equipment, as the fuse panel took the hit and protected everything else.

Just something to think about. Not saying you don't have everything connected correctly, but a gentle reminder that most coaches run on 12VDC. ;-)