could you weld with car batteries?

Discussion in 'General Electronics Chat' started by strantor, Mar 28, 2012.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    My little 120V stick welder uses 24V I believe & adjustable up to 110A. I ususally leave it pegged @110A. I was wondering, If I'm ever without mains power, could I simply weld with a 2 car batteries & 200mΩ resistor bank in series? Anybody tried that?
    (yes, I have big power resistors)
     
  2. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    It would not be dependable,I have had a battery blow up in my face.

    I still don't know how long I was out,I awoke to medic's and police.

    My ears ringing, flat on my back ....the battery top missing. I was lucky

    it knocked me away from the acid. Really don't know how far the blast

    threw me. Sparks and batteries don't mix.
     
    Last edited: Mar 30, 2012
  3. #12

    Expert

    Nov 30, 2010
    16,337
    6,821
    Theoretically, yes. I've heard a good car battery can melt a half inch wrench. I've seen a car battery provide 450 amps. That isn't going to last long coming out of a 100 amp hour battery, but I think you could McGyver something if you had to.

    I would also say it might not have been a sparked hydrogen explosion that Loosie found. A 9v battery gets pretty hot when you put in your pocket with your keys. The heat from shorting a car battery could casue a serious meltdown.

    Anybody try that? Lay a steel plate or a long wrench across a healthy car battery and see if it discharges before the case melts?

    Please don't try this at home! You might not have a home when the battery lets loose its full fury.
     
    strantor likes this.
  4. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    I lost a really nice pocket knife to a car battery. I was laid over the front of the truck with my head & most of my torso down below the level of the hood, stripping a wire. I reached above and behind me for a flat surface to lay the knife down, and BAP! I crawl out and found my knife with a big chunk blown out of the blade. i had set it down across the battery terminals.
     
  5. #12

    Expert

    Nov 30, 2010
    16,337
    6,821
    I had a 12 gauge wire short on a motorcycle. Just defining that it was a motorcycle battery and the engine wasn't running. It was easy to disconnect the wire because it was so close to melting that all I had to do was tap it with a stick to cut it in half.

    If a motorcycle battery can do that, a car battery would melt a 12 gauge wire like it was a fuse!
     
  6. cgalpin

    New Member

    Mar 28, 2012
    18
    1
    Although I am not advocating anyone trying this, I can tell you that you can weld with batteries just fine. I had to do this in a pinch once using jumper cables (which eventually overheated) and got the job done, but then made a kit to allow me to weld with 3 batteries in series when needed. This can be handy for example when you are off-road far from civilization and need to make a repair.

    DSC04563.JPG
     
    strantor likes this.
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Hmmm ! we had a wrench incident. I believe the guy ended up in hospital.
     
  8. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
    1,531
    Got my expansion type watch band between a positive battery cable and ground(frame) once. Had the band pattern burned into my wrist.
     
  9. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    That's awesome! thanks for posting.
     
  10. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    This is what i use & carry in my caravan & yes do the welding as far as posible from the batterys. Using 2,5mm rods. These ive posted on a caravaning forum.
     
    strantor likes this.
  11. radiohead

    Active Member

    May 28, 2009
    474
    31
    Determine how much current your welder draws. This will help determine the gauge of cable you will need. Use H=B/A Divide the battery capacity (B) by the load current draw (A). This will give you the time that the batteries will last. You shouldn't draw more than 1/3 of the capacity of the source batteries to prevent the batteries from heating up due to excessive current draw (the rule of diminishing returns).

    I would advise, as stated above, that the batteries be kept at a safe distance from the welding table in a well ventilated area. For added safety, consider feeding the battery cables into one of those square-D circuit breaker boxes so the line would have a circuit breaker/fuse.
     
    strantor likes this.
  12. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    So no current limiting needed? I figured without current limiting, it would shoot straight up to the 600+ cold cranking amps listed on the battery and blow holes & puke metal. guess not.
    I also thought that the positive would be the electrode and the negative would be the clamp. That shows how much i don't know about welding.
     
  13. BSomer

    Member

    Dec 28, 2011
    433
    106
    It can be both ways. At least that is what I know about welders. I think it depends on what your welding and what stick you are using. Though I could be wrong as well.
     
  14. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    For DC welding its usually + to the work piece. There is no need for circuit breakers, the current draw will be high when striking the arc then lower depending on arc distance. You do need to be reasonably good at arc welding to use 24V as its harder to strike the arc due to the lower voltage. This set up is used & carried by quite a few off road campers for repairing stuf that gets broken when out in the bush. The average camper here in Australia has acess to 2 batterys, one in the vehicle & another for runing acessories such as fridge/freezers. With arc wellding its all about practice & more practice till you get good at it.
     
  15. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    Can one weld just as good with batteries as with a welder, assuming one has the skill to weld with 24V?

    Is there some limit to how long you can weld with batteries safely, maybe a thumb rule, like " don't weld for more than 30sec at a time, then wait 10 min"? I'm assuming the batteries will get hot, not sure if that's the case.

    What's the capability of welding with car batteries? What I mean is, my welder is only advertised to weld up to 3/16" steel. Can the batteries do better than that? How capable are they?
     
  16. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    Its not a system you would keep using, its more used for emergency repairs to get you out of trouble. For serious work better to use your AC welder.
     
  17. Lundwall_Paul

    Member

    Oct 18, 2011
    220
    19
    I have seen a guy working on his car not sure what he was doing but the battery went a good fifty feet in the air and came back in several pieces. He was one lucky guy. I would never attempt welding using batteries,
     
  18. Lundwall_Paul

    Member

    Oct 18, 2011
    220
    19
    Joke> I guess you could try it and if it blows sue the manufacture because it didn’t have a warning label in 500 languages. Again just a joke.

    Don’t weld with a battery.
     
Loading...