How to turn an alternator into a welder

Updated July 20, 2017

People have a unique ability to overcome obstacles in their life. Perhaps the best at doing this are the mechanics and construction-type people. Those who make a living from repairing and creating things just seem to have a natural ability to adapt and overcome obstacles. There is no better example of this than the car alternator powered welder. Somewhere somebody broke a part of machinery and had to find a way to fix it. They came up with a welder that is not only fairly easy to build, but one that actually works. Best of all, you can build one, too.

Wire the alternator. Open the bonnet. Cut a length of 4 gauge wire that will run between the positive battery post and the alternator's "Field" terminal bolt.

Place terminals on the wire. Cut the wire with wire cutters. Use wire strippers to strip the end off of both ends of the wire. Using wire crimpers, secure a terminal end onto each end of the wire.

Create a welding lead. Cut another piece of the 4 gauge wire to use as a welding lead. This should be 8- to 10-feet long. Strip both ends with your wire strippers.

Attach the welding lead. Connect one of the ends of the wire to the "Output" terminal bolt of the alternator and tighten it with a wrench. Connect the other end of the wire to the welding electrode holder. Tighten the connecting bolts with a wrench.

Connect the energising wire. Connect an end of the wire you cut to length in Step 1 to the "Field" post of the alternator. Tighten the bolt with a wrench. Connect the other end of the wire to the positive battery terminal. Tighten this connection with a wrench.

Clamp a welding rod into the electrode holder. Place a jump lead end on the frame of the vehicle the "welder" is on. Place the other end of the jump lead onto the piece that needs to be welded. This will ground the piece. Put on your dark glasses. With the engine running, make your weld.


Set the engine idle at approximately 5,000 to 6,000 RPMs to weld heavier steel. Lighter metal can be welded at a normal idle.


Never watch a welding ark with your unprotected eyes. Wear dark glasses to prevent eye injury from the bright flash.

Things You'll Need

  • Ford alternator
  • Wire
  • Wire cutter
  • Wire stripper
  • Wire crimper
  • Wire terminals
  • Wrench
  • Welding electrode holder
  • Welding rod
  • Locking pliers
  • Jump leads
  • Dark glasses
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