9V said:you are ALWAYS supposed to disconnect the battery(s) when welding on a vehicle
What shop do you go to??? If I smoked an electrical system welding on a vehicle at the collision shop I work at, I would get my ass chewed. Not to mention if the shop manager wandered by and saw me welding without the battery disconnected. I ALWAYS disconnect the battery, just for good measure. Can you weld with it still hooked up, yes, I know many who do, but why take the risk for 30 seconds worth of work???Go to any bodyshop and ask them if they do.......nope....its a myth....or maybe we have just been very, very lucky.