Joe Pfeiffer wrote:
"SteveB" toquerville@zionvistas writes:

My SIL is a good guy and treats my daughter good. He can't back a
trailer for crap, though. He put two nice dings in my truck so far,
and I've had to repair two trailers.

He comes to me with his Yukon Denali. It has a small 4" x 4" plate
where the plug plugs in that has somehow (?) been ripped off the bumper
right along the original MIG welds.

No problem, sez I. Sez he, "Aren't you going to disconnect the battery
so it doesn't foul up the computer?" I really don't think it's going
to put any electricity into the system, and it's not welding near any
computer type component, so I sez no. But, I tell him I'll check with
the pros.

I've heard to disconnect the battery, and not to disconnect. When is
it (is it) appropriate to disconnect?

I've heard anecdotal stories from people claiming that somehow welding
on a vehicle without disconnecting the battery caused computer
problems. If somebody would come up with a plausible explanation for
how this is possible (even if only for a particular process, like
TIG), when the ignition system doesn't do it, I'd love to hear it.

I've seen that as well and can't figure out why that would be true.

It seems to me that keeping the battery connected is more likely to protect
all the electronics in the car than harm them while welding. It acts as a
voltage regulator so in case there are any currents induced in any of the
wires, it's more likely to clamp the voltage levels to 12V instead of
allowing them to rise to higher levels that could do some harm. The only
thing I would expect to be protected by disconnecting the battery is the
battery.

--
Curt Welch http://CurtWelch.Com/
http://NewsReader.Com/