Welding & frying electronics on the welded item

"JR North" wrote: On cars, clamping next to the weld is risky, ^^^^^^^^^^^^^^^^^^^^ No, that is the right way to do it. What you DON'T want to do is put the ground clamp somewhere else, for two reasons: 1.) Don't give the welding current a return path that could include any electronics. 2.) Don't give the welding current a path that includes any bearings. Disconnecting the battery is not necessary--the welding current isn't going that way, and wouldn't hurt the battery if it did. The battery can handle hundreds of amps easily. And you are right: disconnecting the battery could cause you to have to reprogram a bunch of stuff, including your radio stations and the radio's antitheft lockout.

If reprogramming is NOT the issue the disconnecting the negative battery terminal (Which is recommended for my car) will leave in theory every circuit open and as sunch not ABLE to pass welding urrent through them.

I've heard of an instance where a stainless exhaust was installed without disconnecting the negative battery terminal. After the system was TIG'ed in the car wasnt running right and it eventually required the replacement of the computer to blow it.

I'd rather reprogram a radio than replace an ECM Computer

Brent Ottawa Canada

As a welder in many shops with different backgrounds including heavy truck body fabrication and truck trays as well as light vehicle trays and other light vehicle work i can confirm that it is common established practice in all shops to disconnect the negative terminal at least, and in some places the positive also. For most trucks, and many light vehicles in the mining sector they have a battery isolation switch for safety and turning that off is sufficient.

Having your earth clamp as close as possible to the weld is also common practice, or at least having it in the opposite direction of the electronics. Stray current is hard to predict though, so far better to isolate the battery. Provided earth is removed and all electronics were installed correctly, this is the safest way.

Shaun

There is a "Memory Keeper" tool - essentially a lighter plug and a nine-volt battery- that will keep the various ECM/radio memories powered up when the battery is disconnected. Don't tied the battery cables together and be sure to pull the courtesy light fuse(s).

-Carl