House battery disconnect doesn't seem to disconnect

[johnbro27]

My new-to-us 2004 MADP 6V batteries weren't behaving very well so I checked them and discovered the prior owner had neglected them--looked dry. Sadly the cables are so tight that I can't get all the caps off to fill the cells, so I disconnected the house batteries with the switch in main electrical panel over the windshield. But...when I started unscrewing one of the positive terminals some arcing and sparking happened so stopped.

When I hit the "store" switch position on the battery switch it and the inverter/charger panel both went dark, so I assumed there was no power to the coach. Any idea why it would be sparking when I started to remove the positive cable?

[Jim_HiTek]

There are many 'phantom' loads on the batteries from various pieces of equipment in the RV. The CO and Propane detectors, the steps, the radio memory, the engine ECU and Tranni TCU memories and so on. The disconnect switch removes many of the unnecessary loads, but many remain.

Best to remove the grounds rather then the positive cables. But do it quickly. Now-a-days there are large battery switches you can put right at the battery but I just remove the grounds. Note that your engine and tranni will need to relearn your driving habits over the next 200 miles. Your radios will need the clocks reset too.

I also store a pair of rubberized gloves in the battery compartment so if the positive cables have to be removed, I push them inside the gloves even though I unplug from shore power. It's best to unplug from shore power while working, remember that the converter needs a load so the batteries must be there (house) to provide a load. That's for older RV's. Newer ones have it shut off automatically but if you don't know if that's true, then disconnect from shore power when removing batteries.