I'm looking for a decent spot welder.

What welder are you using?

Thoughts on this one.

https://a.co/d/dkAoLZ9

Guys-

Before us R/C ers gave up on round cells, we used to solder them end to end. No matter how many spot welds you use, you are going to create higher resistance connections than soldering. Make a fixture out of a piece of particle board with a pair of parallel 1/4 inch dowels glued to it about 1/2 inch apart. Rough up, flux and tin the end of each cell. You need a relatively big iron with a large tip as you'll be re-flowing the ends of both cells at once. While the solder is molten on both cells, quickly withdraw the iron and slide the cells together, the fixture keeping them aligned and parallel. Connect the "sticks" with suitable size wire. It takes a little practice and just the right amount of solder is critical. If for whatever reason, you think the joint is suspect, quickly snap the cells in half and try again. The connection seems to improve with time so either break it immediately or you're pretty much stuck with it.

You can get 100C 1200 to 1500 Mah 5S  Lipo cells in "block format" with comparable weight as 18650s. Round cells are for old laptop PCs and R/C Transmitters !

Cheers,

Steve Manganelli
P.S. I could find nothing on Internet about the end-to-end soldering, though it was routine in the R/C Electric Community before LIPOs.

Quote from: Paul Taylor on December 25, 2025, 07:55:35 PM
I'm looking for a decent spot welder.

What welder are you using?

Thoughts on this one.

https://a.co/d/dkAoLZ9

When I first started making my own Li-Ion battery packs I purchased a unit very similar to what you listed. Mine was a Sensi 11000 mAh unit. All appeared to be fine. However, after several sessions of making sets of batteries, the penetration of the spot welds became weaker with the welder set to the highest setting. Even after cleaning the tips and a full charge, it got to a point that I could very easily pull the nickel silver strips off the terminal with my fingers. I ended up having to use tinned copper strips and soldered my last set of Li-Ion batteries together, which worked well. It just takes more time to prep the cells to put packs together.

A good friend bought and gave me a Docreate spot welder and it works extremely well, with plenty of adjustment to obtain the perfect penetrated spot welds. You can literally burn a hole through the .2 mm nickel strip and the battery terminal! Don't ask me how I know.

I highly recommend this unit: https://www.amazon.com/dp/B0BD1ZRSZW?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1


Enjoy,
Dennis

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