welding thin sheet metal can be done with a stick welder after about thirty years welding experence.that is an exaggeration but not by all that much.psfred is right it is quiet easy to destroy your alternators diodes welding on an auto with an electric welder especialy when welding that close to it, you can take the battery cables off the battery the connecting wires off the alternator or best take the alternator out of the car when welding electric welding can also be death to a computerized car,I often braze or gas weld for this very reason.
William Rogers.....