ok maybe I am thinking about this to late BUT. I have built my On Board Welder (OBA) setup. I built it to be able to help others on the trail (in my group) the thing is I know given my history that I am going to need it sooner or later.

so My question is how to I protect my electrical system while welding on my own vehicle? I have heard just reverse the polarity but that sounds to fishy. won't it just immidiately short when I put the + lead to the frame since it will be the ground then??

here is my setup:
- old ford unregulated alternator
- ran off the 2nd pully on my York
- OBA is ran off the alternator.

pic is worth a 1000 words:
http://www.printroom.com/_vti_bin/ViewImage.dll?userid=sethpeters&album_id=86596&image_id=8&param=17350

more here:
http://www.printroom.com/ViewAlbum.asp?userid=sethpeters&album_id=86596

You can only weld on yourself with positive electrode, when you weld on another vehicle you can use negative electrode (reverse polarity) which allows for easier welding in awkward positions. Just keep the vehicles far enough apart that nobody could touch both at the same time.

PS: Atlanta is spelled like this, not "Atltanta". Buy a shorter belt for the welding alternator before that one slips. Replace that honking huge air pressure switch with one of the pretty little ones.

I never spell correcly so Atlanta was a typo.

the belt has never slipped yet and I have done alot of welding with it so far. and what are you talking abuot with the pressure switch.. this one works great and has never failed. and who cares if it is a little big.