I've often hankered after a spot welder but I don't have 150 to splash for a decent one and nor would my most occasional use justify it

 

However, I keep seeing cheap all in one type pens, often specifically called out as 18650, welders. The price is well under 50 usd which is fine for me

 

Here are some examples but akiexpress and bang good have many similar

 

Any advice here experts? I just want simple, cheap option for battery welds only.

 

I shall add few examples below

[£21.86 60% OFF]1S Mini Spot Welder Welding Machine DIY 18650 Lithium Battery Nickel Belt Spot Welding Portable Household Fiber Welding Machine Professional Tools from Tools on banggood.com https://banggood.app.link/ATg7A2YtV7

[£26.92 38% OFF]4V-12V Mini Spot Welder Welding Machine Energy Storage Spot Welder 18650 Battery Spot Welder Professional Tools from Tools on banggood.com https://banggood.app.link/R95Z1k3tV7

#Aliexpress ￡31.49 50%OFF | 6 Gears Adjustable Mini spot welder with Type-C Interface Quick-Release Pens Spot Welding Machine Spot Welding Pen for18650 https://a.aliexpress.com/_B1XJZR

I have two reservations about them. Firstly, I can't see how to replace the electrodes. Electrodes wear quite quickly and you don't want the thin part too long, otherwise they get hot. If you can find one that definitely has replaceable electrodes, that would solve it. The other thing is that they're only recommended up to 0.12 thickness, and I use 0.15 nickel strip.

 

The slotted strips take a lot less current to weld because it can't take a direct route between the electrodes, which wastes a lot of current. I slot plain nickel strip by plunging a thin cutting disc on a Dremmel into it, but it makes a lot of mess. You can buy slotted strip, but you have to make sure that the slots have the same pitch as your cell spacing, and they never tell you what the pitch is.

 

In conclusion, I think that it might work for laptop batteries and packs for lights, but looks a bit weak for ebike batteries.

I have two reservations about them. Firstly, I can't see how to replace the electrodes. Electrodes wear quite quickly and you don't want the thin part too long, otherwise they get hot. If you can find one that definitely has replaceable electrodes, that would solve it. The other thing is that they're only recommended up to 0.12 thickness, and I use 0.15 nickel strip.

 

The slotted strips take a lot less current to weld because it can't take a direct route between the electrodes, which wastes a lot of current. I slot plain nickel strip by plunging a thin cutting disc on a Dremmel into it, but it makes a lot of mess. You can buy slotted strip, but you have to make sure that the slots have the same pitch as your cell spacing, and they never tell you what the pitch is.

 

In conclusion, I think that it might work for laptop batteries and packs for lights, but looks a bit weak for ebike batteries.

 

Thats really helpful, Thanks Vfr

 

So, I think, that if I can find

 

1. one with easily replaceable electrodes, and

2. One that can cope with 0.15 non slotted nickel strips (though I have a dremmel and could buy slotted as well in mitigation)

 

Then that's the worst of the downsides sorted. Just what I needed to know. I'm really not out building ebike packs, just the odd repair and maybe super small pack build.

 

I use nickel strip when soldering but never paid attention to the thickness much (as it didn't matter!)

If using lipo as a power source 3s is needed for 0.15mm nickel with variable power control so as not to cause burning with the weld, 4s is needed for pure copper 0.1mm.

Recent work on ES say's that 3s can do copper in a nickel over copper sandwich approach.

I don't think any of them will do pure Nickel Kirsten and the last one states 0.1 -0.12mm Nickel plated. NP has low weld resistance compared to pure nickel.

The K welds and malectrics utilise current to about 1300a and use adjustable pulse rates to get solid good welds twice the current of the cheap ones you have linked to, the cheap ones might be ok for steel plated with Nickel.

The only way to know is to buy one and test by welding nickel or plated stuff to a craft knife blade and then peel it off with pliers to see how much effort it takes to remove, also looking on the reverse of the blade will indicate how or if they burn thru which on a cell will cause damage due to to heat.

Edited July 7, 20205 yr by Nealh

I stumbled across this cheapy one on Ali but I can't see anything about replacement tips but could they be easily made/copied?

https://www.aliexpress.com/item/4000465285054.html?pvid=a4236339-c04d-4ca8-8dfe-daed6ef4af24&aff_platform=link-c-tool&sk=2hfmO5EY&aff_trace_key=cb03d0186fe74428968ff4f23d21355f-1594501260316-00124-2hfmO5EY&rmsg=do_not_replacement&scm=1007.23534.124736.0&terminal_id=98548e457bbd4008ae7810a8a096943d&aff_request_id=cb03d0186fe74428968ff4f23d21355f-1594501260316-00124-2hfmO5EY

I notice with the Kwelds one, the spotweld measurement is adjusted by joules (energy?) and the malectrics adjustment is in millisecs time. Which is the better method?