So I was smelling the rotten egg smell and tracked it to the area of the batteries. Thanks to this forum I discovered that this was most likely due to overcharging. I have two 100 watt solar panels on the roof of my RV to keep the batteries charged with a controller. Last summer in Montana I was hosting at a spot with no electricity. I do not use an inverter, so I was only using power from the panels for the lights, igniters for propane water heater and refrigerator and for a charging station. Maybe on an occasional cold morn I would tun the furnace for a short time. Still I kept have occasions that the batteries were drained. The control unit never charged above 12.6 volts. So, I disconnected it and that solved the problem. Now I have been traveling the southern route n the US and recently got the smell above not only on the trailer, but also in the tow vehicle. Is it possible the panels were putting a charge to the truck battery? Should I now look into replacing all batteries affected? Is there something I can do, short of disconnecting the controller to keep batteries charged when I return to Montana for the summer hosting job? If I need to replace the batteries in the trailer, I guess I should switch to golf cart batteries. How does the wiring change for that?