[BusNit]

I didn't disconnect the batteries and had no issues but don't take my advice. What I would suggest is after you do disconnect batteries is to put your welding clamp very close to the weld area. Keep the coach plugged in to shore power but leave the shore power breaker off. This gives another ground path protection. DDEC still retains power even if you switch the batteries off from the Cole Hearse switch so physically disconnecting for prolonged welding is the smart thing to do. Those ECU's are around 4-5k and getting someone to come to the house to remove/install and program it is where your wallet gets thinned out