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O/T Mig Welding Procedure Question

Discussion in 'The Hokey Ass Message Board' started by TexasDeuce, May 13, 2011.

  1. TexasDeuce
    Joined: Apr 23, 2001
    Posts: 465


    This might come across as an off topic question but then again it might keep someone from getting their ride caught on fire.

    Here is my question.....When using a mig welder on a vehicle, are you supposed to remove/disconnect the ground cable on the battery? If this is not done will it cause a fire?

    Here is what happened to me:

    I took my car hauler/parts chaser -- 1995 Dodge Ram 3500 Dually truck to a muffler shop to get a hanger welded on the tail pipe to keep it from hanging. The guy put it on a lift and began welding the hanger on the frame. He was using Lincoln Mig welder and he placed the ground clamp on the frame.

    He seemed to be having a hard time and kept moving the ground clamp around to different spots. Soon after another dude came and messed with the settings on the welder, the first dude resumed welding and after a couple of minutes, the horn on the truck started to go off then smoke started coming out from under the hood. The fuse box that is under the hood by the battery caught on fire.

    After all the excitement and one empty fire extinguisher later, I brought my truck home.

    Several people have told me that the fact that the dude did not disconnect the battery is what caused the fuse box to start on fire.
  2. customs by jason
    Joined: Oct 3, 2010
    Posts: 207

    customs by jason

    it can mess up the computer on newer cars if u leave the battery connected while welding on the car. i know people who weld all the time with it connected and nothing has ever happends i do know one guy that fired his computer on his car welding and it cost a shit load to replace so i always try to disconnect them just for that reason
    Joined: Mar 6, 2008
    Posts: 1,527


    Ive always heard you should disconnect the ground any time you weld on a car
  4. Welding on an rubber isolated exhaust system with ground on the frame. What path did the welders current follow? The frame to ground straps and cable to the battery thru the engine to the exhaust pipe.

    Welding and computers don't mix at all and its a very very Good idea to have the battery disconnected before doing alot of different things welding is one of them.
    Last edited: May 13, 2011

  5. dragster dude
    Joined: May 21, 2010
    Posts: 194

    dragster dude

    wot he said^^^^^^^^
  6. harpo1313
    Joined: Jan 4, 2008
    Posts: 1,971

    from wareham,ma

    so whats the verdict on the damage?always ground to the pipe your working on.
  7. buckd
    Joined: Nov 29, 2008
    Posts: 335


  8. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,884

    from Oregon

    Sounds like an idiot was doing the welding! He shouldn't be using the vehicle's gorund system to ground the work he was welding. If you're welding on the exhaust, then ground to the exhaust. If you ground to the parts you're welding on then voltage wont travel through other grounds.
  9. kkustomz
    Joined: Jul 4, 2007
    Posts: 342

    from Texas

    He was not a welder for one, I would check and make sure your exhaust is not about to break off. You do not need to disconnect anything when properly welding on a vehicle.
  10. Toner283
    Joined: Feb 13, 2008
    Posts: 1,326


    I was always taught to disconnect the tach too to prevent it from becoming a paperweight.

    The battery is one of those things that will probably be OK if you do not disconnect it but when it only takes a second to unhook it, why take a chance?
  11. Da Tinman
    Joined: Dec 29, 2005
    Posts: 4,226

    Da Tinman

    not removing the negative cable can cause problems with any and all computers, also with msd stuff it can screw up the tach circuits in the box.

    why take a chance? disconnect the grounds then weld.
    Joined: Aug 10, 2008
    Posts: 2,595


    Its hard to get good help these days
  13. Most muffler shops that I've encountered use gas welders for that specific reason. They don't want to have to fork over the dough to repair the damage caused by the electrical interference.
  14. sbin
    Joined: Mar 30, 2011
    Posts: 100


    Not a welder but have dealt with a production exhaust shop for 20+ years that uses mig.They bent a duel system with cross over on a Mustang II and have done all my work since.
    Pulling the batteryground is the first step in a lot of jobs.Most shops do not because customers complain about resetting user functions and clock.
  15. Docco
    Joined: Mar 23, 2007
    Posts: 286

    from Ippy

    The welder has to find its way back to an earth and if the battery (that is earthed to the chassis/body) is still connected it will earth through the electrical circuit on your car.
    Its a no brainer for the exhaust shop guys to disconnect the battery its the first thing they do!! He didn't and you should make him pay.
    END OF STORY he messed up.
  16. gallagher
    Joined: Jun 25, 2006
    Posts: 180

    from califorina

    i know there is a box you hook to battery before welding on newer cars tool trucks sell it. i replace more computers and abs units from exhaustshops/body/shops welding on cars
  17. blue 49
    Joined: Dec 24, 2006
    Posts: 1,275

    blue 49
    from Iowa

    I used to work in a production body shop. One day one of the techs was migging on a quarter panel and had the ground on a wheel stud! I'm sure he had the battery unhooked, but the current had to be going thru the bearings of the rearend.
  18. coolbreeze1340
    Joined: Aug 18, 2009
    Posts: 1,342

    from Indiana

    x100 on putting the ground on the piece not the frame. Always remove the ground when welding on anything with electronics. Also, keep the ground clamp as close to the welding as you can without being in your way.
    We have to weld on a lot of structure and equipment at work and we always keep our grounds close to keep current from passing thru bearring and such.
  19. TexasDeuce
    Joined: Apr 23, 2001
    Posts: 465


    Thanks for the info everyone. I figured that was the problem but i was too pissed to even think about it when i was there.
    I have been back to the shop everyday since it happened and the owner is not there. I have called several times and no one speaks english so when I start talking in spanish they just hang up.
    My wife is telling me to just avoid the aggravation and blow them off because they are not going to pay for the repairs.
    I am not after the money, it is the principle of the matter. I am going to have to use the "pen is mightier than the sword" approach and pay a visit to the better business bureau. It might not do much but maybe it will open their eyes and even prevent some other sap from getting his car burnt up.
  20. Actually I'm surprised the truck is running after a fuse box fire.
  21. The BBB wont do shit. Get it fixed, keep your reciepts and take them to small claims.
  22. gearhead1952
    Joined: Dec 17, 2006
    Posts: 305

    from Arvada, CO

    How does disconnecting the battery do any good? You are only removing the battery from the circuit. The computer and all the rest of the electrical parts are still connected to ground. I leave the battery connected and find a good ground as close to where I am welding as possible.
  23. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    Member Emeritus

    Just a bad operator. Always clamp the ground as close as possible to the joint and never to the frame unless you are welding on the frame. You can't control the path that the amps take unless you control where the ground clamp is placed. You don't have to move the ground for every joint as you work your way back but I will move it to the other pipe on a true dual system.

    I welded everything on my exhaust systems with a mig for 20 years and never once had a complaint about an electrical problem. I can't count the number of computerized SUVs that I put a converter back system on. They kept me in business until their gas mileage killed their sales.

    People like to think if you can get an arc everything is fine but you do need the consider the path that the amps take. If you do that you will not have any problems. The same theory holds true for battery ground connections on hotrods.

    The amps required to melt the wire apparently was traveling through the electrical system on it's way to the joint. Did you drive it home? I would not have taken it until they had made any required repairs.
    Last edited: May 14, 2011
  24. Deuce Daddy Don
    Joined: Apr 27, 2008
    Posts: 4,971

    Deuce Daddy Don

    bingo!!!!!!!!!! We have a "winner"----best advice!!!!!:d:d:d:d
  25. TexasDeuce
    Joined: Apr 23, 2001
    Posts: 465


    I didn't drive it home. I had to get it towed home. The fuse box in the engine compartment and half of the battery melted to crap.

    Hindsight -- I should have left it there and made them fix it.
  26. Missed the tow truck somewhere after empty fire extinguisher.

    What's your insurance say? They will recoup from the business. You can probably assume all the electric components took a beating. Computers, modules, switches, motors, you get it.
  27. 61bone
    Joined: Feb 12, 2005
    Posts: 890


    Went to a friends shop recently where he was welding on the radiator support. He had his ground hooked to the battery negative. I moved it to the support for him and he got all bent out of shape. He put it back and said its gotta have a ground. I went home. Hes driving the car so it must not have hurt it.
  28. bonez
    Joined: Jul 16, 2007
    Posts: 3,493

    from Slow lane

    i always diconnect the battery whn i weld, but sometimes it happened that i forgot to do it and nothin bad happened..still, i try to remember.
    61 bone dude, i woudt do that! once i hooked the ground to small bolt that was goin thru a apanel, very small, it was a 3M, and after about 5 minutes it melted and the clamp fell off, it was brass alright, but considerin that electriciy produces heat i wouldnt risk to transform my battery into a bomb, i kno its a very slim chance, but why take it?? or burn the battery anyway.
  29. With it connected to the battery? Lol

    Sometimes you can put a cigarette out in a gas can, sometimes it explodes.
  30. blt2go
    Joined: Oct 27, 2009
    Posts: 551


    31vicky you kill me!!!! but you are absolutely right. i always disconnect both leads to the battery and clean a grounding area nearest the spot to be welded. never had an issue. i think it's because i do these things. bottom line you can get lucky just like 31vicky pointed out, but that doesn't make it right. sorry to hear this happend and good luck.

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