Actually, it is very much like a battery charger. It's a Solar brand, which is a common brand of service station battery charger. I figured they could build good welders if they knew how to make battery chargers.
I bought it used ($500 with cart, argon tank, extra wire and several hoods--not bad). I didn't get the instructions with it, but I called the manufacturer's tech support and they were really nice, even though I didn't buy from them directly. They're mailing me an instruction manual. They also helped me identify when it was made and lots of other helpful info.
By the way, do you know if it is possible/reasonable to operate such a machine on an extension cord? It came with a real heavy duty 220 extension cord, about 20' long. I had never seen one before, and thought it might be a bit dodgy. If it were ok, however, it would be convenient.
Best holiday wishes to you and everyone on the list.