Hey there fellow eskaters, I made an Spot Welder using a 600W Microwave and an Arduino and Relais. But when I want to weld a 0.15mm Nickelstrip onto an 18650 battery it doesnt really hold well, its not strong enough.
I am measuring about 1.5V on the secondary winding (using a 35mm² Wire). Also here are some pics if that would help.
@Zentaria I had exactly the same issue, I had the pulse set to about half a second and would see the nickel glow but the weld was crap.
I added another loop to the secondary winding, voltage went up to 3.5 or something and now I need a pulse with of 0.01s to get a nice strong weld.
So try adding another winding to the secondary coil.
Are you pushing hard? I had the same problem and almost exactly the same setup. No matter what time I put in welds were weak. Than I read somewhere that force that you use is very important. Now without changing anything I’m making welds that won’t let go (have tear nickel strip) and my time setting is 0,25s. I’m just touching nickel with electrodes and it works perfect almost zero pressure.
In commercial spot welders there usually is a double pulse weld, the first short pulse like up to 10ms if im not mistaken is meant to soften the material and the second completes the weld. And yes you better be pushing hard on that weldspot. Also, try adding a small cut with a dremel or something in between the electrode touching points on the nickel, makes more current go through the cell casing, ergo better welds. You can see this on all of the chinese premade battery pack nickel strips as well.
Also for trying another loop you might just strip that fat ass insulation and wrap the wire in kapton or somehing, I bet you will have plenty of space left.
@LukePL 0.25 s welds are insanely long my dude you need moar powaaa I bet your cells get rather toasty.
Yes it should, if your welder has the balls or it. But this thing can help a lot. I was surprised to see the difference with and without that cut.
@LukePL hell man, idk, rewind the transformer like @JonathanLau1983 mentioned, use some fancy mosfets for activating your welder as relays usually have some “bounciness” to them, not sure, but it could compromise the current output to the weld spot.
And if you are going full balls to the wall making many battery packs, you might just go ahead and get a k-weld
https://www.keenlab.de/index.php/product-category/kspot-welder-kit/
We have this at work, powered by 5 supercapacitors in series (2.7 V and I think 1200F each), god damn that thing can weld anything. I personally love it. The darn thing decides on the weld time on its own, because you set the power output in joules. Yea, its smart