Unno. When I used to spot-weld sub-C NiCd cells, I’d take a thin strip of metal, put a dimple in it where I’d want the weld to be, securely have one contact go right to the cell, and the other end to the tin strip. Carefully lower it down into place, and ❋pouf!❋, the arc would weld that critter tight.
Used a few of beefy caps, like 80,000µF power-supply caps with screw terminals, in parallel, with ~14ga wire coming together at the “probes”.
Was enough to “stick” a screwdriver to whatever it’d touch, so…
Maybe not for critical applications, but for connection a few batteries a DIY effort is fine (It is easy to test if the welding works and is solid enough).
The cheap Chine spot welder and the DIY design, will probably work about the same and the DIY design may last longer.
I don’t think any of us are proposing to use this for high precision manufacturing of battery packs. Welding on button tops, or building a multi cell battery pack is closer to the truth. Perhaps even rebuilding a cordless tool battery.
The instructable linked has a video that shows the build process. I shall attempt to link it here que’ed up to the place where he starts testing it.
Be forewarned, you may want to have your safety glasses on before clicking the link.
^ Peter, watch that video and realize the cells remain wrapped. There’s also multiple welds on each cell on each tab. So the likelihood that a single tab would have 4+ welds fail for the tab to come completely loose and short something is not going to happen I dare say.
Fwiw, when I’d spot-weld sub-Cs, I’d do it with the cells essentially side-by-side, then fold then over to be coaxial (ie, a battery “stick”). So having a mil-spec weld wasn’t necessary, as they’d be just lying in a trench or rack and not get jiggled around too much. Soldering was pure Hell, but a quick spot-weld made things lots easier.
I built a mot welder last year. I control it wth a footswitch to a relay. Most of the time it works well but I have a twitchy foot :person_facepalming:
I’ve been trying to think of a way to do a timed double pulse. Wonder if I could use the timing part of the circuit. Hmm?
The version of the board I ordered has an auto pulse feature which would require no use of a foot switch. It sees both probes are in place on the strip, waits 2 seconds, and then pulses the welder.
It will possibly work for low drain applications where there is a strong spring to hold it in place, and the button top never gets any side load (twisting).
AFAIK, a magnet won’t do any good, as the button top is non-magnetic material. (I’m likely wrong about this, though.)
For anyone wondering, professional battery spot welders (resistance welders) use the two probes side by side, not top and bottom like a traditional spot welder. So no need to access the underside of the flat top.
I have used some very high end Miyachi welders at work, the two copper electrode tips just sit side by side, how far apart depends on the type of cells, tab material, etc being welded.
Would love a simple setup like this DIY welder for home use on personal projects, and I see no reason a good weld couldn’t be made with something like this.