I posted this some place else…I guess I thought I posted here…
This seems a bit better
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I’d grab 3 of those pcbs if you still got em. Pm me your info and price.
CD Welder I like this, it’s like your’s but instead of the pcb just uses a big rectifier. Do you think it will work well? From what I remember @whitepony is using something similar?
So still playing with some free time but hitting the pool today so just a few shots…
Sanded down copper rods for electrodes so they have tips fine enough to fuse the nickle.
What diameter do you use for the copper rods ? I have finished the instructable arduino version but I am still wondering how big I should go with the soldering tips …
this is extremely dangerous.
or, how to blow up a car battery 
Can you elaborate on that ? Do you have arguments / bad experience with this setup ? JP Spot welder (also a battery welder) is used by many people. I have not heard of such an accident.
I plan to put a 200A slow fuse is serie with the spot welder. What can possibly happen then ?
That’s just shorting out the battery, which is not great. it also has no safety mechanisms so if something metal shorts the contacts and welds on, you’re fucked.
If I have a 200A fuse in serial, a short will just blow the fuse, I guess, right ? I do not see the very high danger … but I’d be happy to hear your view on this.
even with the fuse, you are shorting out a battery. thats how it makes the heat required to spot weld. but when you short out a battery it damages it. it might work for awhile but over time it will degrade and fail at some point, possibly in a dangerous way. The spot welders that use transformers are going to be the best, but i would but capacitor based ones right behind them, and then battery ones if you have no other option.
90% of the time its going to be perfectly fine to use a battery one, but that 10% can be dangerous.
I see, thanks for the explanations. Well, I do not plan to use mine for more than a couple hundreds of batteries. That should do.
If I go for a larger amount, I’ll probably consider building this one http://www.avdweb.nl/arduino/hardware-interfacing/spot-welder-controller.html
Honestly … It’s good for a couple of spot welds…but not a true solution to replace the real thing
never EVER ask that question out loud where lithium and extreme current is a factor. Skatan will show you “what could possibly happen then.” DOOM. CHAOS. THE BURNING TIMES.
Also i’ve seen them built with those huge car stereo supercaps and they seem to work well with those too. I do enjoy seeing this kind of thing done. Ultimately i ended up buying a sunkko but i was originally planning to build my own. What kind of thickness can you weld with something like this?
Today I finished my spot welder. Here are results, I’m pretty happy with it, and it was waaaay cheaper than cheapest option on aliexpress.
https://www.youtube.com/watch?v=brkA9j_55J0&feature=youtu.be
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I agree it’s dangerous …but a momentary switch can resolve the issue of the contacts welding accidentally to the piece you are welding
The arduino spot welder has a foot switch. I am pretty confident that stops one of the electrodes welding unless you push the switch.
you would have to use a relay, but yea that would increase the safety factor by a lot.
Oh and running a long line away from the battery lol like outside lol
I’m ordering all the parts needed for an arduino spot welder. Once I’m done, I can post a mouser order list and update once I build it. Going to be welding a 10S4P battery for my new board. I ordered the PCB’s through Bay Area Circuits.
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