Under hood welder

I've been looking around on line for a underhood welder and found one that boasts a welding Amp capability of 150-1200 amps.... It runs off of some high out put generators, and I'm wondering if they can be tied in as an altenator, or if it has to be it's own system... Waitin on an emai back on that. If you guys want to look it up, google Zena welders.... I can't remeber the link.... Anyway, I'm gonna buy one when I get the cash saved, I'll let Ya'll know how it works