The energy storage welder has no voltage

What voltage does this welder use?

This welder uses standard 110 volt AC line voltage. The system comes complete with power cord, weld cables and gun. Just add the accessories required for the stud size to be welded.

How to spot weld a capacitor?

Most spot welders use two points near each other or on each side of the workpiece. The current from the capacitor is probably just absorbed by the relatively large piece of metal. The second video below from [American Tech] shows a 500F capacitor doing spot welding with little more than two wires and it seems to work.

What is the problem with using a capacitor as a welding tip?

The problem is in how the discharge energy is being directed. Just using the capacitor would cause the charge to flow out as a spark when you got near the point to discharge. To combat this, [Julian] put a microswitch between the capacitor and the copper point he expected to use as the welding tip.

What is the difference between a spot welder and a capacitor?

The other thing we noticed is that he used a single point and used the workpiece as a ground return. Most spot welders use two points near each other or on each side of the workpiece. The current from the capacitor is probably just absorbed by the relatively large piece of metal.