Its an old idea I first saw it in writings by Nessmuk (George w. Sears) and Kephart (from the early 1900s). The only "new" part is to make it out of steel.
If a person needs to weld something it is possible to use 2 or 3 (2 should be adequate) lead-acid automotive starting batteries in series, that are in good shape, along with heavy duty jumper cables, a welding rod holder (stinger) and at least #10 welding lens to protect your eyes from the harmful U-V and ultra bright light generated by the electrical arc.cutting goggles are not enough ... along with welding rod, of course.
I don't really recommend doing it; but if you do USE EXTREME CAUTION , IT CAN BE HAZARDOUS.
I favor (6010) 1/8" rod for random (dirty) off road and/or agricultural applications. but pretty much any rod in the 1/8 to 5/32 inch range can be used to weld with batteries
Be aware that there is a potential for battery explosion and fire along with eye damage, including blindness, if you don't use proper welding eye and personal protection.
Also chipping the slag from the welds makes it go every where; use eye goggles, (its as sharp as broken glass).