Would anyone like to chime in. I recently made an MOT spot welder for 18650 nickel strips. I can reliably weld 0.2mm nickel. Although I do need a slit if I'm doing nickel <--> nickel (stacking for more amps).

My main problem here is that I had to use 2 parallel transformers since I can't source a single more powerful one e.g. 1500w

The current ones are around 700 and 900 watts. Together, they manage around 20 amps from the wall 220v, that's about north of 4kW, so I'm guessing 2000 amps at 2 volts in theory.

In practice, I'm probably closer to 1000 amps due to heat and smaller electrode tips near the end for the spots.

Any ideas if raising my voltage to 4 volts would help with welds? I might also switch out my SSR since it seems to be sagging on that end. I measure more amps on the free directly connected cable from time to time, versus the one coming from the SSR.

Edit: The cables on the secondary windings are 16mm2 or around 6AWG. I'm confident they can handle the load since I can't really feel any heat in them. They barely heat up after 5 seconds of a constant short. I'm doing mostly 50-60ms pulses for the welds.