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 ...
Spot diameters of about 1 mm are realistic. To create even smaller weld seams, fibre lasers can be used. Because of their better beam quality and efficiency when compared with Nd:YAG systems ...