Hand held/portable spot welder - anyone try them?

So, more and more frequently I find myself wanting to, or needing to, rebuild 18650 battery packs. Ideally, these would be spot welded - not soldered. The ones I’ve done are just soldered. So far, that’s been okay. Not ideal - but ok.

I was wondering if anybody has purchased or used any of the handheld/portable spot welders obtained from the usual suspects: fleabay, ali, etc.

For my purposes, I’d be only doing a few packs a year, so this is definitely a low use item which is why I am avoiding a more expensive machine. Also, I’m only using nickel strips or the existing tabs on packs now that I’ve found a way to (usually) remove the tab without much damage to be reused.

Let the scolding commence. :wink:

I was looking at this kit.
I haven’t pulled the trigger yet, but it looks like a more reliable system than what’s on eBay or Ali.

That’s probably a more reliable kit, but it’s also a lot more expensive, which I was trying to avoid.

I have a cheap one that seems ok. I’m powering it from an old car battery but a newer battery or a lipo pack would probably be better. I had to shorten the power leads to get enough current for a reliable weld.

I tested it on an old cell first and then built a replacement 10.8v battery pack for a Makita drill a couple days ago. Holding together so far.

I might buy one of these too

I was in the same boat. I wanted to upgrade a few of my Dewalt packs, but couldn’t justify anything fancy. I ended up going with one of these $25 jobbies:

I heard about them on a facebook group, and decided to beef up the PCB traces with some solder before ever powering it on. It’s been a real champ. I literally just used it again a few hours ago when my daughter brought me her purse and asked me to re-attached some spot welded loops to the metal bar. My previous solder attempt didn’t last.

I won one in an ebay pure auction for $6! I built it last weekend with a new 8582d soldering station. A fellow on eBay sells lightly used agm batteries for $45, and I’m going to give one of those a try. I also have two 1800mah lipos…

Take a look at the kWeld. It’s very popular among powerwallers.

Hi Joshk,

Can you post a link for your spot welder? I have a few Makita packs I’d like to rebuild.

Why did you add solder to the PCB traces, was this a known issue with these or just being safe and adding current capacity?


I looked into the kweld seriously, and had a lengthy conversation about buying one on their Facebook group. But this sums up my decision:

And really, I got to realizing the best thing about the k-weld was that amazing battery they recommend. So I bought that battery, and the little red spot welder. It works great, and consistently.

Well I can, but it says page not found these days :slight_smile:
I added solder to the PCB traces because I saw a post where someone blew one of the mosfets, and it looked like a thin bottleneck in the distribution trace/solder was to blame. They thicken the PCB trace with solder from the factory, but don’t do it enough. When mine arrived, there appeared to be a thin bottleneck too, so instead of risking a mosfet, I just beefed it up.
I actually bought 2 more of these spot welders to beef up and offer to the Powerwall community, but by the time they arrived I had stopped visiting the group page, so they are still here. If anyone wants one, PM me. For cost I will send one as-is. For an extra $10 I will add/solder a yellow XT-90 battery connector, beef up the traces, and make the electrodes dome-shaped so they don’t have sharp corners to sink into the molten weld pool.