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.

How many SuperCap capacitors should a spot welder have?

Supercapacitors tend to have higher internal series resistance than a corresponding electrolytic. For example, this 1.6 F, 16 VDC supercap bank could theoretically store ~200 J, but on connecting to the low-impedance spot welder, most of the energy is lost heating the capacitors. Perhaps two or three of these banks might suffice.

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.

How does a 500F capacitor work?

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. Hackaday’s own [Sean Boyce] even made one out of some whopping 3000F caps.

What causes welding defects?

Welding defects can be caused by the presence of areas of local anomalous overheating of the alloy and can be asso-ciated with the formation of discontinuities in the process of plastic deformation , which requires further research. Fig. 1. Discharge energy of the capacitors of the spot welding apparatus. The inset shows the welding process.