This is one of 9 Sony’s that I harvested from a NOS laptop pack. I accidentally dropped it about 3 feet and put a slight dent in it. It still performs normally with about 2500 mAh capacity but the wrapper is turning color in the area of the dent. I believe the translucent Sony wrappers are treated so that they turn color in the presence of a leak. I have seen this effect in old worn out SONY IMR cells.
The dent.
I do not trust this cell and will safely discharge it and drop it in the recycle bin.
take that one outside now!
that dent could cause a short at any time.
Doesnt take much does it? Not that a 3 feet fall is insignificant.
I dropped a Samsung once too. That one I charged and discharged with normal results. I left it on my desk in the discharged state and found that it had leaked all over the piece of 8 1/2 by 11 paper it happened to be on. Good thing it wasn’t charged up at the time it decided to barf all over my desk.
And no, it doesn’t take much.
That looks bad. there is a high chance the internal “layers” could short at any time, also it may be leaking under the wrapper, or somehow the casing is rusting/corroding under the wrapper. I would not keep that inside at all, but leave it outside in a metal bucket until it can be recycled safely.
the middle pair of a 3S2P pack…
Do you vape?
It’s interesting to see cells in this condition. If it continue leaking can we see more pics (as long as it is safe to do so)?
I wonder if this is the physical damage or the g-force that’s causing it. Because if it’s the latter, then dropping a torch from a height could do the same thing?
That is a combination of both. It can also happen to any battery. Even though I do not always follow this rule, all batteries should be charged and stored outside of the living space regardless of what their internal composition is because they all have the potential to cause destruction whether be it subtle or violent. If you knew what I knew you would not even park the car in the garage.
Regarding the dropping of a light or a battery by itself..I have done so many times. Usually all is ok but until the battery can get checked it gets placed aside to avoid a mishap. This applies to ALL batteries, not just our 18650's.
This really does concern me because this cell STILL performs normally! Before I send it off to the recycle bin, I took it outside for one more “night on the town” I fully charged it and discharged it in my B3100, outside at night. Here is the result, scary, huh? Like I said, the SONY wrappers are especially good at indicating leaks.
Here is a pic from just after I discharged it in the B3100. I pealed back the wrapper to expose the cell underneath.
I was going to cut through the cell with a Stanley knife to inspect the casing. I want to determine that the corrosion is coming from within and not from without. But maybe I should fully recharge it and put it outside in a safe container and see what happens? That something could take years though so I think I will operate, but only AFTER I discharge that cell down to 0V! Right now off the charger is sitting at 3.28V. There is still some energy in there to cause me a problem when I make the cut.
BTW, can anybody confirm my presumption that a totally “dead” cell will not release any energy when I make the cut? Or am I headed for trouble?
No, why do you ask? Are those that do at more risk if something goes wrong with a cell?
Nice to have you here again, HearAgain. 
I have had a spring in a flashlight wipe out a protection board! I have also had them dent the bottoms of cells, I wonder if THAT can lead to problems.
Just one more thing to worry about…………………
I think I’ve had an old cells similar to this that could do discharge to good capacity, but could not keep it for long. It was either LG or Samsung laptop pull.
Somehow your picture reminded me of that cell, though I’m not sure how similar the condition was, but I’m pretty sure that scenario applies here. You can charge and discharge it normally, but there is already an internal short that slowly discharges the battery.
It’s just that the short is high enough resistance that the charger couldn’t detect charge leakage. But let sit for several days and it will show the voltage drop.
I tried opening a 0V soft pack from a tablet, didn’t seem to have anything reactive anymore. As usual, no guarantee use safety PPA if you do try it.
>> Do you vape?
> … Are those that do at more risk if something goes wrong with a cell?
Same risk as holding your flashlight in your mouth when the battery explodes,
https://www.google.com/search?q=e-cigarette+fire
and then under /More, do an image search
It looked a little like what happens to VTC5's of some vapers. It's usually liquid and easily fixed by replacing the wrapper, but some suspect micro arcing.
After opening a small Sony Li-po cell from a phone (was bulging and smelt strange, quite sweet) I’d wear a respirator and do any surgery outside. Whatever is leaking, if it can corrode metal it might not be good to breathe. If there was any gases under pressure surely it would vent already? Or maybe it is close to venting… 
The inside of the metal casing, I wonder if it is totally corroded (and slowly migrating).