Feedback on spotwelds?

[cellmate]

Hi all,

I have this spot welder: https://endless-sphere.com/forums/viewtopic.php?f=14&t=89076

I'm powering it with a 5000mah 50C sustained 100C burst 3S LiPo, welding 0.2mm pure nickel strips onto 18650s.

According to the official documentation and what I've read in forums about this welder, I should expect good welds at 7ms burst length, but I'm finding that the bare minimum where I can get a weld strong enough to really hold (ie: the nickel rips when trying to pull it off) is 16ms with a double burst! The 7ms weld basically just falls off with a little nudge. However, at 16x2 the nickel strip gets quite warm instantly, so I'm worried I might damage the cells. So far I've only been testing on old broken cells, not my good ones.

On a razor blade, I can get a strong weld at something closer to the advertised burst. I've read that blades are a good analog of 18650 cells, but that doesn't seem to hold up in the experiments I've been doing.

I've tried cutting off the raised positive terminal of an old 18650 after welding it to see underneath where I made the welds. I didn't see any visible scorch marks (as I do on a razor), so I guess it didn't burn through? Assuming all parts of the cell have the same thickness and grade of metal, it should be good...

I've attached some pictures and a video to demonstrate the strength of the welds, and to show the cell after the welding. Can you guys give me an opinion on whether the cell looks like it got too hot? Or suggestions on how I can do better welds with shorter duration bursts?

Thanks!

 

[999zip999]

You can clean and scuff the nickel strips and battery cells alcohol swabs and scuff pad and or
what are the shapes of your tips you don't want them to a full pony after you get a real point you want to round them in a bit you know what welder do you have ? Do you have a link to the welder ?

 

[cellmate]

You can clean and scuff the nickel strips and battery cells alcohol swabs and scuff pad and or
what are the shapes of your tips you don't want them to a full pony after you get a real point you want to round them in a bit you know what welder do you have ? Do you have a link to the welder ?

Sorry, beyond the suggestion to clean and scuff the nickel, I didn't understand the reset of your suggestion. The welder is linked at the top of my original post.

 

[999zip999]

Sorry it is there good. Now to the biggest question I asked what is the shape of your tip how did you grind it is it two pointed it needs to be rounded off a bit. Ok
Okay the way it looks to me your welder doesn't have a big enough footprint it's not supposed to be a pinhead.
What welding tips do you have 80/20 or tungsten
or puree copper. More info

 

[goatman]

those 18650 cells are dead, dead at 0-volts, my eyes when i saw your pictures

 

[cellmate]

what is the shape of your tip how did you grind it is it two pointed it needs to be rounded off a bit.
...
What welding tips do you have 80/20 or tungsten or puree copper.

Two pure copper wires, insulated with shrink wrap, rounded and sanded a bit to work well at a 45 degree angle. Here's a video of someone else using the welder from the other thread; I use it pretty much like he is doing. https://www.youtube.com/watch?v=voWpcxBbxoA

those 18650 cells are dead, dead at 0-volts, my eyes when i saw your pictures

Yeah, they're dead 0v cells to practice on.

 

[jonyjoe303]

what size wire are you using on your spotwelder? I have the malectric spotwelder and originally I was using 8 gauge copper clad cables for the probes and I was getting weak welds even at high power settings (70 to 80 power) and the cables were getting very hot after a few welds, too hot to hold. Also they were jumping around everytime I did a weld.
I replace the probe cables with 6 gauge pure copper welding cables an that fix my problem. I was getting good welds at 40 power, and the cables werent getting that hot, I could finish a project at one time without having to stop to let the cables cool down.

Picture of my probe 6 gauge pure copper cables, I use copper nails as probes which work good.

 

[cellmate]

what size wire are you using on your spotwelder? I have the malectric spotwelder and originally I was using 8 gauge copper clad cables for the probes and I was getting weak welds even at high power settings (70 to 80 power) and the cables were getting very hot after a few welds, too hot to hold. Also they were jumping around everytime I did a weld.
I replace the probe cables with 6 gauge pure copper welding cables an that fix my problem. I was getting good welds at 40 power, and the cables werent getting that hot, I could finish a project at one time without having to stop to let the cables cool down.

I just measured the wires: 1.8mm diameter, so about 13awg. Mine also jump around on each weld, and the tip gets uncomfortably hot after a few welds.

I suppose I could look at upgrading this, but it's a bit annoying, as I specifically bought this unit since it was a well-liked ready-to-go unit with a small footprint that people had reported success with on 0.2mm nickel.

Thanks for the input.

edit: The TIPS are 13awg and get hot. The wires are much thicker and do not get hot.