Spot welders for 18650 batteries

[caiser01]

My company has a gadget we're building in house that uses one 18650 battery each. The power leads are soldered to 0.15mm nickel contacts that are welded to the battery. We've been using one of the cheap, MOSFETs+lead acid battery type welders (the red PCB one with the modifications recommended in various places) for the early units but the results have been...variable (nickel contacts popping off the batteries during field trials, etc.)

It seems as though the market is flooded with cheap, battery-powered and slightly more expensive AC-powered spot welders from China.

My question: Is this all you can get now or is there something better?

I've searched online but I keep coming up with all the same usual suspects (Glitter, Sunkko, U.S. Solid).

Ideally, we were hoping to find something that runs off AC power (120V preferred but we could make 220V work if needed) that you can get replacement parts for when/if needed. Does something like that even exist?

Are there other brands than those mentioned above? What were people using years ago before all these China battery welders appeared?

Eventually, we'll be building 2000+ of these gadgets and I want to make sure we're not being let down by poor tools. If the answer is, "The cheap tools work perfectly. You just don't now how to use them properly", then please enlighten me    This is something that's a bit new to us and we want to get it right.

[Messtechniker]

You might consider this:
https://www.keenlab.de/index.php/product-category/kspot-welder-kit/
Expensive, but seemingly well made.

[sam512bb]

You might consider this:
https://www.keenlab.de/index.php/product-category/kspot-welder-kit/
Expensive, but seemingly well made.

I tried a few other options and the results were poor and so I ended up buying the KeenLab kspot welder and I have been very happy.  The device is sensitive to any drops in your voltage source and so keep the voltage inputs as short as you can.  I ended up using a charged auto battery for my energy source, short leads, and the results were excellent.

You can buy the battery pack plastic shrink tubing and thin conductor strips from Amazon, Ebay, Aliexpress, etc for low $.

[thm_w]

"It seems as though the market is flooded with cheap, battery-powered and slightly more expensive AC-powered spot welders from China."

So then get an AC-powered one, no? That should be the most reliable and consistent. I would avoid anything battery powered, at the very least go for supercap.

What is the budget?
https://www.sunstonewelders.com/collections/battery-welding/products/micro-welding-parallel-weld-head
https://www.aliexpress.us/item/3256805388860453.html (not sure if this one is transformer or capacitor)

[caiser01]

So then get an AC-powered one, no? That should be the most reliable and consistent. I would avoid anything battery powered, at the very least go for supercap.

What is the budget?
https://www.sunstonewelders.com/collections/battery-welding/products/micro-welding-parallel-weld-head
https://www.aliexpress.us/item/3256805388860453.html (not sure if this one is transformer or capacitor)

Multi-thousand dollar is probably not in the budget but I really wanted to see what one of those was like for comparison and those were what I couldn't find in my searches so thanks for the link.

It seems as though the kWeld in combination with the kCap ultracapacitor module and a current limited DC supply might be the way to go. That would give us an AC mains powered solution that's within budget. I've seen a fair number of positive reviews of the kWeld on this forum and elsewhere, and the fact that there's detailed documentation for it is another pro.

The various Sunkko, etc. 737 type welders interest me but I'm a little weary because of mixed reviews in different places. What's the repairability of these units like?

[thm_w]

Cheap transformer units are very basic inside.
I'm sure kweld is fine, though I would not personally use it in production without some sort of metal enclosure for everything to go into.

https://www.eevblog.com/forum/reviews/sunkko-709a-spot-welder-teardown/

[jerryk]

Has anyone tried this brand of spot welder or similar type?

https://ussolid.com/spot-welding-equipment.html

I'm considering the BSW06 or BSW07.

Jerry

[caiser01]

Looks as though Glitter, Sunkko, and U.S. Solid are all brands of the same Chinese parent company: https://glitterwelder.com/brands/

Haven't tried any of these but I'd imagine the product offerings are similar across all three brands.

[artag]

I wouldn't bother with the cheap ones for production equipment.
If your volumes don't justify the expensive ones, buy cells with a strip of nickel already attached. then you can safely solder to the nickel.

[jerryk]

As far as cheap goes, I was thinking that the two US Solid models that I'm looking at are on the expensive side of things.  I have yet to find anyone with direct experience on this new line of super capacitor based spot welders.  I do like not having a battery to tote around like is needed with the KWeld.  So it's between the KWeld and these Glitter brands right now.

Jerry

[voltsandjolts]

My question: Is this all you can get now or is there something better?

If you got $10K USD then give your money to Amada for one of their capacitor discharge welders. Very nicely built. There are older versions of these, such as the Hughes HCD 125 that pop up on eBay, also branded Palomar or Micro Join.

https://www.eevblog.com/forum/projects/homemade-spot-welder-keeps-blowing-mosfets/msg3580031/#msg3580031

https://www.ebay.com/itm/313617743953

I rev eng'd the HCD125 schematic, I have it somewhere.

[dnordquest]

"I rev eng'd the HCD125 schematic, I have it somewhere."

Would be interesting to see!

[voltsandjolts]

"I rev eng'd the HCD125 schematic, I have it somewhere."
Would be interesting to see!

It was fairly simple really. Rectified mains fed to a resonant converter whose output charged a capacitor bank up to a maximum of 400V or so, adjusted as per user setting for weld energy 10 to 125 Joules (hence name HCD125) i.e. weld energy setting E = 0.5 C V^2.  The real gem in the unit is the output transformer that the capacitor bank gets dumped into, where the pulse width setting selected the primary tap. The secondary (direct connect to output/welding handle) was about 5 turns of copper busbar    Some pictures in my link given above.

[Kean]

I have a Glitter 801D battery welder, and for small jobs it works reasonably well with just a bit of experimentation to suit the tab thickness.  It does take a little while to charge up the supercaps, so you can't use it at a moments notice.

I bought it to replace my old spot welder when it started to play up.  That was a basic model mains power unit I had for about 10 years, similar to the current model Sunkko 737G.