tig welding on cars that have computers

[Railmen]

He had it grounder to the bumper and when he welded chain there it was fine but when he welded a piece of chain to the hood that’s when it blew. Good thing the hood was closed! Yes it was a new battery, that’s what we all got a kick out of.

Well i highly tend to think that the battery did not get the welding current but more of along the line of a spark finding the hydrogen in the battery and that is what blew up, i have seen two batteries blow up from sparks in my short life time.

One blew up when the guy took off the charging cables from the battery and a small spark from the post to the clamp caused the venting battery to go BOOM, poor guy had ACID burns up his arm and face.

Railmen.

[nfinch86]

Hi, I never disconect the battery, I have a Surge Protector for the battery.
I just hook it up to the batteries posts before I weld on any vehicle, of course I also attach the work lead directly to the part I'm welding !!

............. Norm

[eyesolator]

The hydrogen thing is interesting. I spoke to one of our auto tech teachers this morning to try and get some info. on the battery thing. He said the battery blowing up was probably due to hydrogen as apposed to a massive charge caused by a welder somehow making it’s way through the battery. He also said the he would always disconnect the ground on a battery because all of the critical sensors and computers are grounded directly to the battery and by disconnecting the ground to the battery you have effectively isolated them. Sounds good to me?
He also mentioned the “Maintenance Free/sealed” batteries have a check valve on them to prevent flow or fire back into the battery. Because of this they are supposedly less likely to explode. He went on to say about the ground being on the area of welding ect., and made the comment that probably not many muffler shops are disconnecting batteries to weld muffler systems together and it works out just fine. Me I’ll error on the side of caution and disconnect the ground on a battery.

[Sberry]

The battery doesn't "tie" anything together, they are already hooked together before this point.

[Sberry]

Here is another way to think about this, there is a hundred thousand + trucks being used as work platforms every day, every kind of welding being performed on the beds of them every hour of the day. None of them are unhooking anything. You are about 200 times at risk blowing something up hook/unhooking batteries which is a COMMON cause of explosion as you would be leaving well enough alone.

[BSParts]

General safety procedures seem to advise disconnecting the battery anytime you are doing any work to a car. Not to protect the battery from you, but to protect you from the battery if you do something silly.

[Tryagn5]

Welding on anything which has multiple computers or single computers is a very risky situtation. I always disconnect the battery ternimals before I do anything. I work on heavy equipment for a living and have seen what happens to computers. Most damage is done if the grounding circuit is poorly grounded or to far from the arc. The voltage saturates the computer circuit playing havoc with the system. In fact Case has issued bulletins addressing this probelm....ALWAYS disconnect the battery, I have even gone as far as removing the computer.
Kevin

[nfinch86]

Hello; I'm Not an Electrician, But think about it, Welding is Electricity. The Welding Current travels from the welding machine to the point of the Arc, then returns Via the Work lead ( Ground Cable ) !!

Ity's Not going to Roam around all over the place, It's going to come from the Welder to the point of the arc , then return by way of the work lead to the Welder !!

In addition to the obvious practice of attaching the Work lead to the point of the arc ( The Piece being Welded ) I also use a Surge Protector Specific
to the job of welding on Vehicles !

Just My Two cents,
............ Norm

[Sberry]

How many times have you seen damage done? Thousands and thousands and thousands of welding operations everyday from welding trucks, you would think we would hear stories every day here if it was a problem? Also thousands of operations at body shops as well as plenty at muffler outfits, I cant even recall a single post on 3 or 4 forums over 10 yrs of a problem with welding on cars.

[Bodybagger]

Disconnecting the battery is primarily to prevent accidental starting of a vehicle that's being worked on, with the worst case being started in gear.

Of course, nowadays, cars have automatic transmissions, and even the once with manual trannies won't crank in gear. So this precaution is a holdover from the olden days.

The other consideration is to prevent fans and fuel pumps from activating. Disconnect the battery and you have disabled the fuel pump.

And finally, the other reason is to prevent short circuits while working around the engine compartment.

Imagine being under a car with the front end on jackstands and accidentally jamming a wrench across the starter solenoid lugs... If it's a manual and it's in gear, it will fall on your face, then run forward just enough to stop on your chest. Of course, none of that is possible with the battery disconnected.

As far as the computer is concerned, they go bad on their own. If one goes bad after you've welded on the car, you will be blamed. It makes perfect sense, even if it had absolutely nothing to do with it. And ESPECIALLY if you disconnect the battery... after all, that amounts to "tinkering with the electrical system."