18650 spot welding -how to- ULTIMATE REPOSITORY

[flippy]

I've heard this, but also seen plenty of reviews saying it worked fine. It sounds like you either get a good one or a lemon. I can always return it if it doesn't do the job.

welding heavy duty strips and long runs will kill the transformer.
people that had no problems are the people doing tiny batteries, not big ones.

[Allex]

I've heard this, but also seen plenty of reviews saying it worked fine. It sounds like you either get a good one or a lemon. I can always return it if it doesn't do the job.

Why not go for something better? We have two great options here and both are already much better than sunko at what they are supposed to do. I can weld 0,3 strips without any issues and my JP welder has gone through tens of thousands cells without any issues.
viewtopic.php?f=31&t=68865
viewtopic.php?f=14&t=89039&hilit=kweld
https://www.keenlab.de/index.php/produc ... elder-kit/

[jonescg]

I guess I didn't know where to start. Reviews seemed to suggest the 709 was better than the 788. But also, I have zero interest in building my own welder. I want an off the shelf product which works as described. If it fails I'll either repair and upgrade, or send it back and try something else.

[Allex]

You dont have to built it, just order a finished one and connect it to a battery.

[bigbore]

I have both the spot welders Allex suggested and have been spot welding with a 3S5P lipo battery I made some years ago with old cells from an e-scooter and I still be able to make battery packs for local buddies.

[tomjasz]

So I have ordered a Sunkko 709 AD

please cancel that order as fast as humanly possible.
that thing is nothing but grief.

Eggs Ackley!

Although my early version KWeld is a turd too. Jumped to soon and updates beyond my skill level make it a $100 visually interesting paperweight. My JP Welders rock on.... Listed for sale, the KWeld, without a single bite. In fairness there is an offer fro me to send back, $25, pay for upgrades, but I understand not all the way to the latest iteration, for additional fees. Look. It’s all good, but for a fella that just wants a welder that works... JP.

[Taswegian]

Whats the problem with the early K-weld?
I have a relatively recent one and although I've only done a few test welds so far it seems to perform exactly as advertised, ie works great!

[tomjasz]

Whats the problem with the early K-weld?
I have a relatively recent one and although I've only done a few test welds so far it seems to perform exactly as advertised, ie works great!

Protection components need updating, et al.
viewtopic.php?f=14&t=89039&p=1349912&hi ... d#p1349748

[jonescg]

Well my Sunkko arrived and it seems to have come with two hand-held probes. I guess after one heats up too much you can swap leads while the other cools down

[KarlJ]

OK guys so i've just built a B52 Bomber battery 22S10P using LG MJ1 3500 mAh cells
i've used 5mm wide 0.2mm thick solar panel bus tape - its tinned copper.

scotchbrite the tops/bottoms of the cells and tinn them with solder and 80W iron, takes less than a second using fairly heavy gauge solder.

result - far quicker than spot welding nickel (I have a 12V battery type spot welder)
resistance vs 8mm wide 0.15 Nickel is 3x the current carrying capacity.

Bomber pulls 75A max so 7.5A / cell draw which is well within the 10A continuous they are rated at.

After a 40km ride i've eaten through 30AH of the 35Theoretical per the Cycle analyst, battery warm to touch - motor well not so much and whilst I haven't melted the 5304 yet I think the possibility exists.

In all at $11 for 10m of the tinned copper bus bar strip I was just a little short and needed about another meter of it.

have done a botch and connected the end cells to the bike wiring via copper braid and still waiting for the BMS, i think its a viable solution for a home builder vs spot welding which using nickel IMHO is an inferior solution for current carrying.

sag at 6000W is only 3-5V depending on the pack voltage to start with.

Obviously soldering nickel is nigh on impossible so for both performance enthusiasts for the 3x current carrying capacity and home builders without spot welders alike I think the tinned copper is a great solution.
tables tell the story for me
https://www.endless-sphere.com/forums/d ... &mode=view
Karl