Spot Welder (for batteries) Recommendations Please

[FazzaGBR]

I currently 'make' my own CMOS batteries for my Vintage/Retro Laptops I have like this: https://www.retrocomputing.co.uk/2019/03/how-to-replace-cmos-battery-on-compaq_12.html

I basically rip of the current JST connector from the 3V CMOS battery and using conductive aluminium tape, tape it to a new CR2032 battery.

I also have quite a few old laptops that I'd like to replace the main laptop battery by carefully opening it up and replacing the cells but I wont be using the above method to do this for obvious reasons!

I'd love to do it properly using a spot welder but there are so many to choose from I don't want to buy one and it's not up to the job so was hoping someone would already be doing this sort of thing and recommend a particular one or at least certain specifications to get?

I'm looking for replies from people who have one so they know for sure it will do what I need it to do - I can buy from places like amazon.co.uk and aliexpress.com etc.

Thanks!

[WattsThat]

There are of course a thousand different possibilities but for a simple, inexpensive commercial product, it’s hard to beat the Finirsi SWM-20 that be had for about $50. Is it the best? doubtful. The cheapest? No way. But, for the once in a while one-off small pack or just welding tabs on something, it’s hard to beat. Self-contained and a decent interface. It sure beats a $20 Chinesium pc board with a big SCR, a LED interface and a repurposed microwave oven transformer.

https://www.aliexpress.us/item/3256811745083936.html

[thm_w]

If you plan long term use, get a capacitor based unit, they are about $100.

For short term use, the fnirsi might be fine. Just be aware there is a high chance it will fail after some years as the internal battery either degrades or self discharges.

https://www.reddit.com/r/batteries/comments/1g7hutv/doa_died_on_arrival_fnirsi_spot_welder_swm10/

[Smokey]

Funny.  I just tore open a Milwaukee M18 pack to replace a dead cell, and now I need a battery tab welder for a high current 18650.  Timely post.

I have a ton of stuff around the lab, including some huge pringles can style capacitors.  I'm tempted to just dump them into a tab and see what happens.  Anyone know of a good DIY hack tab welder with good results?

[elektryk]

Funny.  I just tore open a Milwaukee M18 pack to replace a dead cell, and now I need a battery tab welder for a high current 18650.  Timely post.

I wouldn't recommend single cell replacing, but if you want completely rebuild such pack, then AWithZ P20B should be sufficient.

This pack was made with P20B using nickel plated copper + nickel plated steel sandwitch.

The cells are tabless Ampace JP30.

[negativ3]

Got one of these a few years ago and it's been a very reliable unit.

https://www.keenlab.de/index.php/product-category/kspot-welder-kit/

[tautech]

Got one of these a few years ago and it's been a very reliable unit.

https://www.keenlab.de/index.php/product-category/kspot-welder-kit/

The story of Kweld development starts here:
https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/

[elektryk]

Does anyone have experience with this specific model? Is it enough for 0.15mm nickel strips?

https://it.aliexpress.com/item/1005010569377604.html

Dunno about this (transformer based unit), but P20B will do.

BTW its hard to source real nickel, especially thicker one.

[eKretz]

I also bought the Keenlab one a couple years ago and it has been great.

[nonius_]

If you plan long term use, get a capacitor based unit, they are about $100.

Wow! That's pretty cheap.

I built my own capacitor-discharge spotwelder years ago, long before you could buy such things in China. Uses 1.56F worth of capacitors (at 25V max) for 450J of energy and a hockey-puck thyristor to discharge the energy into the workpiece. I'm very satisfied with my machine, it does anything I care to weld, including up to 1.2mm stainless steel (1.5 too, but it's a bit hit-and-miss, so I draw the limit at 1.2mm SS). And I always use it with a foot switch.

Wouldn't want to miss my CD-spotwelder for anything in the world, it's a very useful addition to the lab.

BTW its hard to source real nickel, especially thicker one.

I got my rolls of nickel battery tab strips from a nearby company that specializes in rebuilding battery packs. And recently was given a bunch of nickel sheets by an electronics friend, who got a large supply of them when the Philips CRT-factory in NL closed down.

That supply will last me for the rest of my life

[Smokey]

Funny.  I just tore open a Milwaukee M18 pack to replace a dead cell, and now I need a battery tab welder for a high current 18650.  Timely post.

I wouldn't recommend single cell replacing...

True.  I'm actually replacing one whole parallel section (3 cells in parallel).  One cell likely had an issue and that section was drained all the way near 0V and sat there for a while, which damaged all 3 cells.  The rest of the pack is fine.  I characterized all 3 damaged cells and at this point there was not one that was obviously "bad".  They all just equally sucked (higher than normal ESR and about half capacity).
I will also balance each section of the pack (3P) separately before I toss the pack back on a charger. 

[Smokey]

If you plan long term use, get a capacitor based unit, they are about $100.

...
I built my own capacitor-discharge spotwelder years ago...
Wouldn't want to miss my CD-spotwelder for anything in the world, it's a very useful addition to the lab.
...

Beautiful piece of equipment.  Great job.  Super clean. 

[MathWizard]

That C.D one a few posts above looks nice, I'll have to look up a schematics to see whats going on, and how much current a typical one puts out.

I've seen welders I think of various types, that are the size of large toasters or maybe small microwaves. How small do they get tho?

I still have a MWO transformer, but never had a real reason to make a welder, but some of the youtube ones are fine and safe enough.

[FazzaGBR]

After much thinking on how much I wanted to spend etc. (and local availability) I have gone for the AWithZ UKF10 for £85 from Amazon UK so I got it the next day after ordering it!  I've just unboxed it and had a quick read of the (short) instructions so can't wait to give it a try!

As recommended, it's a capacitor based one and seems pretty easy to use..

[FazzaGBR]

I can confirm that the AWithZ UK10 is a great spot welder than can handle with ease and simplicity spot welding batteries!  With a Gear setting from 1-100, setting 8 is spot on (pun intended) for spot welding button batteries so it should be able to handle all other tasks with ease.  I've tried using the foot pedal (which works great) but I personally prefer the push button that is on one of the probes.

Now I need to select one of my retro laptops I want to re-cell the battery on and work out where the best place to buy affordable replacement cells from...