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The following is a discussion from another list and indicates that simple welding need not be considered high tech. I think one member of each survival group we will need to know how to do this. If we have electrical power available in one form or another then welding will be possible.

Does anyone have experience with 12 volt welding? What equipment is needed?

My experience has been you need over 20-25 volts to be able to decently strike an Arc and hold it. Optimally one needs about 40 to 50 volts (open circuit) for easy arc welding. Spot welding can be accomplished by use of much lower voltages and higher amperages with the need to have a heavy gauge good conductor in good contact with both sides. The area is heated and melted until both piece's stick together. 1-6 volts can be used if heavy duty conductors are used up to the points of contact. Usually used to stick or spot weld thin sheet metal together. Both surfaces need to be cleaned and must make good electrical contact at the point of the weld.

To Arc weld I once used two 55 amp alternators mounted where an air conditioner used to be on an old car. The output was wired in series and gave about 24-30 volt open circuit. The current through both stator coils was controlled by use of a large variable resistor and was wired to the battery of the car. This worked well but I found myself wishing I had used 3 alternators or more voltage. Makes holding an arc much easier. The current you need depends on the size of rod you use. One needs bigger rod for welding thicker material. It doesn't matter how one delivers the voltage and the current - batteries, generator's all will work. Some control of current is needed. This could be on the input side of an alternator or the output side of a string of batteries. A salt water resistors can be made from a 5 gallon plastic bucket and metal plates or copper tubing. Change resistance by amount of salt, distance between plates, and changing surface area in the water. I like the idea of using metal strapping material as a variable resistor in a pinch.

One trick that I have been told that helps if the voltage is low and striking an Arc is difficult. Wind some heavy wire around a large chunk of iron to make a large inductor. Wire this in series with one of the welding leads. This will store energy when the rod is stuck and give you an instant of more voltage when the rod brakes loose to help form that initial arc. This was used effectively with a 24 volt aircraft 200 amp DC generator to make a welder.

Offered by Mike.