I was thinking of getting some PCBs produced and to solder them. Since the fabricator for PCBs has quantities in multiples of 5 I’m going to have more PCBs than I personally need. I was wondering if there’d be any interest in the community for either a pair of these excess boards to assemble yourself or even ones I would assemble.
They’d be based on this intractable http://www.instructables.com/id/DIY-Arduino-Battery-Spot-Welder/
I figured I would ask in case anyone would be interested.
Interesting, but I have only taken packs apart and have never wanted to make them or weld on tabs.
I’ve been fixing my tool packs as of late and then when I saw this post in the pulled from the recycle bin thread it made me do some research.
Not really a fan of soldering right to the cells.
I’d be interest in a welder powerful enough that can weld button top caps vs thin metal tabs. I don’t know if one like this could spot weld buttons or not
Some people have reported that it does work on .3mm thickness material which is what the the button tops at fasttech look like
https://www.fasttech.com/p/2157805
Those are what you’re referring to right?
I might build one or two of these and I’m just down in NE Indiana so if I had to send one to someone to ‘borrow’ to test it with button tops I’d be open to that 
I’m not going to ship a car battery though lol
The boards I’m getting go up to 1000A of welding current where that ebay one goes up to 800A so the DIY one would be more powerful
Yes, I bought a bunch of those caps and gaskets from FT. The flat area measures .4mm
I’m very interested. I have seen that instructable before and thought about it myself. The creator has a website in the EU selling kits and some of the ‘custom’ parts.
One thing that has held me back is my confidence in getting the current version and the right BOM ordered. The ’ible claims there has been a new rev of the board this month.
I did order the newest 2.2 version boards. I’ll keep this thread updated with progress. It’ll be 20 or so days for the fab in China to make the PCBs and them to get here via HK Post (largest delay is the shipping time).
Man, I’m interested, but don’t have a lot of extra spending money right now! I actually have some batteries and a BMS that I bought to make a pack, and haven’t done it yet because I’m not sure soldering the tabs is a good idea for high draw battery power tools.
Are you talking bout just the pcbs or the whole BOM? I am interested in the pcb and the alu profiles. But depending from where you live it might be cheaper for me to order in EU.
Could really do either. I’m more likely to do more just bare boards than whole BOM sets.
If you’re in the EU it might be better for you to order right from the guys shop who did the instructable
For us in the US it might be better for us to just the BOM stuff locally and not worry about currency conversion/euro value and international shipping
i could use a board or 2
I would be very interested in one of these units. I could build my own, given a BOM. Let me know, what the plan is.
I’m working on a BOM at mouser which I think I have basically complete. I’ll share it once I assemble one to make sure everything is correct.
Thanks, I’ll have look and ask around in my circle if more are interested and just order in the EU…
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.
Exactly, we aren’t building automobiles or aircraft here. It’s not rocket science to spot weld a tab on a battery.
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.
Engage safety squints as some might say…