Did you ever see a thin metal tab bonded to a battery terminal with little pock ... is what led [Erwin Ried] to purchase a small, battery-powered spot welder from a maker in Korea and test it ...

This Spot Welder can be used to weld 18650 batteries. It uses a 12V car battery as welding current supply. Typically one 60Ah 600A battery delivers enough current to get good welds with 0.15mm - 0.2mm ...

a stm32f103c8t6 blue pill microcontroller board. a nokia 5110lcd screen two buttons one foot pedal and one parameter setting push button, jumper wires for blue pill spot welding pen tool with push ...

I did really need a spot welder though, and there was no shortage ... As the supercapacitors were roughly the shape of a large battery, I put a collar around one electrode as a spacer.