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Deforming battery when pulling strip off
Ok so my phone just screwed me over here it is again in short. How serious is a dent in the minus end of a li ion battery. Pulled the nickel strip off and the minus seems to be deformed and there is a noticable dent in the battery.

Should I discard these batteries? Pictures if I figure out a way to send them.
I've formed small dents/humps on many of my cells, without any apparent adverse effects after running them for 8 months. But YMMV.
The positive side is a lot more sensitive, because the safety device (CID) or seal may have been damaged.
Holes that leak electrolyte are a complete different story, though. Get rid of those.
JoneK likes this post
Modular PowerShelf using 3D printed packs.  40kWh and growing.
Thank you for the answer, I tried to find the answers in the forum but didn't find any and ended up posting this Smile sorry if duplicate

Edit, here are the pictures.. Phone is so old and Chrome is too fat for it, couldn't send them from the phone.

The consistent and repeated recommendation is to avoid dented cells. However, the 'dent inward' alarms me more than the 'bow outward' (from pulling off the spot-welded nickle).
If you think about the internals - its a tight role of material spaced very precisely and closely. So a dent inward would squish the material inside, potentially resulting in a 'bad flow' of current. The bow outward at the bottom (90deg to roll) should not harm the insides.

In my own cell processing I would discard the dent inward (pretty severe) but I routinely keep ones with minor bow outward at bottom.

However, as a responsible contributor, I'm sure the forum would flatly recommend avoiding dented cells so beware.
If I plan to solder to the cells, I tend to use flush cutters and leave some nickel trip on the cell. Not only does it reduce the chance of damage, but it’s easier to solder to as well. Even if using in cell holders, you tend to get a lower resistance connection vs one where you don’t have a flush surface because of the spot weld nipples.
Geek likes this post
In the pics you can keep em.
Dents bigger than this and especially at the sides....THROW AWAY
(08-09-2019, 11:21 AM)ajw22 Wrote: ...
Holes that leak electrolyte are a complete different story, though.  Get rid of those.

That would be my biggest concern. If you have pulled on the strip hard enough to deform the metal, it is most likely that you have compromised the strength of the metal shell. I try very hard to just cut the strips rather than tear them off. Unless the spot welds aren't very strong.
(08-09-2019, 06:47 AM)JoneK Wrote: Pulled the nickel strip off and the minus seems to be deformed and there is a noticable dent in the battery.

Not a complete answer to your question but I have noticed that the higher quality the cell to start with (Panasonic or LG) are far more mechanically sturdy and lets you rip out even quad-welded strips with sheer force and no dents and definitely no venting. On the other end of the scale, no name crappy cells not worth the effort in the first place requires serious technique with individual flush cutting and rotating the strips in order not to break the cell to the point of it venting.
No. cells
Indexed: 53
Processed ok, not yet indexed: ~3200
Broken down, untested: ~0
Not yet broken down: ~200 kg
I throw out any cell with a dent, no matter what size it is. It's not worth the $0.20 cents it will take to get another cell. The structural integrity of the cell casing has been compromised and you don't know what the outcome may be.
Oz18650 likes this post
Really guys and gals… just leave a small section of strip on the battery. Most often than not it ends up being an advantage vs trying to achieve a clean removal. It’s certainly better than having a higher resistance connection and potential damage to the battery.
mike, solarsteve, Geek like this post

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