In an emergency, you can use car batteries to weld broken pieces of steel. The current produced by a single car battery will allow an electrode to spark but will not produce enough current to properly weld broken pieces of steel. Wiring multiple batteries in series increases the voltage and the current supplied to the welding area. This allows you to use larger diameter welding electrodes on thicker pieces of steel.
Set two car batteries five to six feet away from the welding area. Slide the car batteries next to each other.
Connect the positive terminal of the first battery to negative terminal of the second battery with the positive side of a set of jumper cables.
Pull a second set of jumper cables apart to create two separate leads. Connect one end of the red lead to the positive terminal of the second battery, and the other end of the red lead to the piece you are welding. Connect one end of the black lead to the negative side of the first battery. Clamp a 3/32-inch welding electrode into the clamp located on the second end of the black lead.
Cover the connected batteries with a blanket. Put on a welding hood.
Set the tip of the 3/32-inch welding electrode at the weld area. Lower your welding hood.
Scratch the tip of the welding electrode on the metal. Lift the electrode 1/8 inch from the surface of the metal. Pull the lit electrode along the metal. Connect a third battery in series with a third pair of jumper cables if the electrode will not create a continuous weld.
Hit the weld with a slag hammer to remove the slag from the top of the weld bead. Clean the weld with a wire brush and add another weld to the metal if the weld did not melt into both pieces of metal.
Allow the weld to cool before using the repaired component.
