I saw that same kind of article many years ago - planned to make one as well for myself. Had a few lawn mowers that I thought I would be able to do it with, but, never had the time to do it and the lawn mowers are now long gone.
Thanks for the reminder - I should see if I can make it happen some time this summer.
I just picked up a lister petter LT engine. I want to build a wvo powered 12v battery charge/welder. It is already set up for dual belts and should chug along nicely at idle to recharge batteries, but it can rev to 3,000 rpms to weld. I already picked up another ford 90 amp alt and regulator. I just need a few things and a long weekend to finish it up.
Saw an article in an old "Mother Earth News" about the lawnmower welder and knew a guy who made one(long before I knew him), said it worked well. He also told me that he tried it without having the battery in place but the initial draw would killed the motor.