Oz18650 said:
chuckp said:
That looks really good.
Can you tell us more about the spot welder you made?
Sorry I didn't take any photos at the time, but here goes.
I had an old UPS for a PC that was no longer useful. I stripped it out just for the case as I thought it would make a good housing for the electronics.
I used a JST41-1200 Battery spot welding control board, 16 single chip microcomputer control, 1602 MCU LCD, encoder double pulse pcb to control the pulse duration.
https://www.aliexpress.com/item/32810563725.html
Striped out an old 230V 850W microwave oven i had kicking around to salvage the transformer, cut out the secondary windings and removed the magnetic shims i replaced the windings with two turns of 16mm2 flexible battery cable with approx 1M of spare cable to exit through the case for each of the spark electrodes.
I mounted the MOT in the case along with the pcb and used a small 230V to 12V transformer for the pcb power supply. Cut the end of the case out and fitted an old PC fan on the end to keep everything cool, not that anything gets hot, I probably didn't need the fan. Pushed the battery cable out through a couple of holes drilled into the front of the case and cut holes for the display board and adjustment knob.
I soldered a couple of soldering iron tips into the ends of the battery cable for the electrodes and covered the ends with a few layers of heat shrink.
Used an old sewing machine peddle switch to operate the welder.
It works very well for welding fuses to cells with pulse power set to about 80% but I do need to have the pulse power set to 100% if I'm welding nickel strip otherwise the weld isn't strong enough.
I have now obtained a 1000W MOT that I'm going to fit in at some stage. I will take a few build photos when I get around to doing it.
I haven't measured the output amperage but I would imagine it's around the 450A mark, the voltage at the electrodes around 1.8V
I found that a two pulse weld works well on the fuses, P1 set to 65% for 70ms (to pre-warm the metal) a 25ms delay and P2 set to 80% for 90ms (for the weld).
The only purchases i made was for the JST41-1200, 230V-12V transformer and 2.5m of 16mm2 battery cable, the build cost was around 35 and a few hours of my time.