On board welder
 

Has anyone built one of these? I am considering the method discussed
at pirate4x4. Below is a link to fabricate an on-board welder using
an alternator. This is the way the $800 plus units function. It
seems straight forward but I thought I would have you all take a look
before I start fiddlin'. One thing that is kind of vague is how to
wire the welder exactly. I have the Ford type setup with an external
regulator. It would seem and is implied in the "GM" version that the
"+" welder lead would be connected to the "+" on the alternator. The
"-" would be ground. The volt meter would be parallel of the "+" and
"-". The power supply is basically there to bypass the
regulator/charging loop (battery) which then allows the alternator to
produce higher voltage/amps. I would assume that the battery is
running the engine until you switch the power supply off. Let me know
what you think. This would be extremely handy and looks like about
$200. This sight is the same sight I have gotten other good tips from
such as my old winch's wiring diagram.

http://www.pirate4x4.com/tech/on-boardwelder/