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!
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!