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How to Make Alternator Welders

by Contributor

There are many types of welders on the market today. They have uses ranging from light-metal auto body repair to full-on heavy steel fabrication. Most people who do welding at home do not require or need a professional type of welding system. They are able to get by with a small home unit. But what about those people whose passion takes them off-roading? These people need an emergency welder that they can operate in the field to make repairs to their vehicles. Luckily, the answer is right under their hood. A welder can be constructed using a car alternator for power.

Step 1

Wire the alternator. Cut a piece of wire to run between the positive battery post and the alternator's "Field" terminal. Cut the wire with wire cutters. Using wire strippers, strip the end off of each end of the wire. Use wire crimpers to secure a terminal end onto each end of the wire. Cut a piece of 4 gauge wire to use as a welding lead. This should be 10 to 12 feet long. Strip both ends with a wire stripper. Connect one end of the wire to the "Output" terminal bolt of the alternator. Tighten it with a wrench. Connect the other end to the welding electrode holder. Tighten the connection with a wrench.

Step 2

Connect the power wire. Connect one 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 opposite end of the wire to the positive battery post. Tighten this with a wrench.

Weld the part. Insert a welding rod into the electrode holder. Place a jumper cable end on the frame of the vehicle the welder is on. Place the other end of the jumper cable onto the piece that is to be welded. This will ground the piece. With the engine running, strike an arc with the welding rod and make your weld.


  • If you have trouble with the welding rod sticking, have a friend press the throttle pedal down on the welder's engine. Increase the RPMs and you will have no problem with the rod sticking.


  • Do not weld without eye protection. You can injure your eyes from the bright light of the welding.

Items you will need

  • Ford alternator
  • Wire
  • Wire cutter
  • Wire stripper
  • Wire crimper
  • Wire terminals
  • Wrench
  • Welding electrode holder
  • Welding rod
  • Locking pliers
  • Jumper cables

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