An Arduino Nano based Spot Welder for battery welding
This Spot Welder can be used to weld 18650 batteries. It needs a 7-12V power source (12V recommended) and uses a 12V car battery as welding current supply. Typically one 45Ah battery delivers enough current to get good welds with 0.15mm nickel strips. For thicker nickel strips maybe you will need bigger battery or two in paralell.
The Welder generates a double pulse, where the first one is 1/8 of the time of the second one. Pulse time of second pulse is adjustable by the potentiometer and displayed on the screen in mS so you can exactly adjust the time. Its adjustable from 1 ... 20 mS.
Watch the Video to get detailed instructions on how to build it.
Due to many requests for the PCBs
If you guys want to buy a set of pcbs to build your own spot welder please take a look in the comments below this instructable. Some people who ordered boards at PCB manufactures are willing to sell some of them. I don't have any more pcbs left for sale.