Damaged cells...

The-J-Man

Member
Joined
May 2, 2017
Messages
263
Greetings,

I have a couple damaged cells that I wanted to ask questions about.

I have 2 NCR18650PF/D cells where the metal on the positive end is partly torn off. Im not planning on using them but does this render these cells useless? or are the cells in theoryjust as safe to use?

I have 1 ICR18650-22P that has been crushed. It came out of a fully functioning hoverboard pack in thiscondition and I have charged and discharged it to see how it performs, and it is flawless! It does not get warm or hot any more during charging or discharging then other cells from the pack. How is this possible?

cheers

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Throw them both away is my tip

the first one have protection under neath in form of a cid. by destroying the top you also malfunctioned that function and that is what keep the cells kind of safe.
#2 you dont know whats going on inside since the crush. The inside is wrapped around it self and there is a certain function with the density. I wouldn't bother. I just did throw out like 8 of em i had crushed... Even though they test fine i dont trust them in my powerwall. I would call that as a bigger issue than low voltage since this can or do cause issues to the outher structure of the cells.
 
daromer said:
Throw them both away is my tip

the first one have protection under neath in form of a cid. by destroying the top you also malfunctioned that function and that is what keep the cells kind of safe.
#2 you dont know whats going on inside since the crush. The inside is wrapped around it self and there is a certain function with the density. I wouldn't bother. I just did throw out like 8 of em i had crushed... Even though they test fine i dont trust them in my powerwall. I would call that as a bigger issue than low voltage since this can or do cause issues to the outher structure of the cells.

Oh I see. So now You got me thinking. the spot welds were so good on all of these NCR18650PD/F's that it nearly always pulled /bent the metal from the positive side upquite a lot. I usually just pushed it back down not thinking much about it. Could all these cells be damaged badly and I dont know about it? I posted in my build thread, they are testing flawlessly.


There is no point in risking to use the crushed and damaged cells,they are all ready in the dead cell box :D
I was in an interesting presentation where they talked about how safe cells are that were in a vehicle that had crashed (discussing the second life aspect of Li-Ion cells from EV's)They scanned the cells and it was astonishing to see the internal damage!
MajStealth said:
i recommend the bin also, better safe then sry, right?

Yeah I had no intention of using them but im curious about how safe they could theoretically be. :)
 
Sometimes those spot welds can be very solid.
 
from my experience, a little distortion on the positive side doesn't really affect the battery's function or safety. Negative side is worse, since there's no space underneath the bottom plate. I'm using cells like this without problems, but you should inspect it carefully and check the protection PCB under the positive pole.
 
The-J-Man theoretically and practically they are not safe. To avoid damaging the cells use something like this or this exactly

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As a side note ebike, eboard, escooter battery packs that are properly assembled are gonna be welded like that. The spot-welds in most laptop packs would split if used in anything like that. On my own eboard packs I can actually see the nickel twisting a bit at the spot-welds but they don't snap apart.(the pack is designed to flex)
 
Wattsup said:
Sometimes those spot welds can be very solid.
Yeah no kidding :D
owitte said:
from my experience, a little distortion on the positive side doesn't really affect the battery's function or safety. Negative side is worse, since there's no space underneath the bottom plate. I'm using cells like this without problems, but you should inspect it carefully and check the protection PCB under the positive pole.
Ah ok, negative side has torn open on quite a few of those cells when i was taking the packsapart.
What should i look for when checkin the pcb?
Scepterr said:
The-J-Man theoretically and practically they are not safe. To avoid damaging the cells use something like this or this exactly
As a side note ebike, eboard, escooter battery packs that are properly assembled are gonna be welded like that. The spot-welds in most laptop packs would split if used in anything like that. On my own eboard packs I can actually see the nickel twisting a bit at the spot-welds but they don't snap apart.(the pack is designed to flex)
Even when its bent back? What could have made them unsafe?
Why did i not think about using a snipper like that before :mad:
These were definitly properly assembled, built like tanks!
The hoverboard packs ive been using use the same nickelstrips and spot welds as the laptops packs but I guess the amps are quite low and therefore its goood enough, or they are just super cheaply made....
 
They are welded like that to be able to handle the current. Generally in higher current applications you have a bit thicker nickel strips and you also weld it better.

The cells are cealed from start and on the positive side you have something called CID. This is a pressure switch you could say. When the pressure goes to high it will disconect the cell. This will for instance happen when the cell is put up for to much heat or to much current during a short circuit.

Imagine if you har torn a hole into the negative side... No pressure can be built up and therefore the CID will not work and stop above scenarios. Same goes if you destroy the positive side. You will then have altered or destroyd the function of the CID making the battery unsafe in events of issues.

Same goes with pressing the CID back with a screwdriver that some people do... This could potentially also make the CID useless.. And the CID did pop due to a reason :)

With this said you will not be able to get rid of the nickel strips on all types of packs and on some you are better of just cutting the strip and leaving the spot welded part.

I dont want to be a party pooper but on the same time i would personally never use a cell with above scenarios.... Atleast not in any application in a house or powering my house.. I though could use them for some toy outside but frankly.. How often do it happen? :) Throw them instead and you dont have to be in bed sleepless :)
 
The-J-Man said:
Wattsup said:
Sometimes those spot welds can be very solid.
Yeah no kidding :D
owitte said:
from my experience, a little distortion on the positive side doesn't really affect the battery's function or safety. Negative side is worse, since there's no space underneath the bottom plate. I'm using cells like this without problems, but you should inspect it carefully and check the protection PCB under the positive pole.
Ah ok, negative side has torn open on quite a few of those cells when i was taking the packsapart.
What should i look for when checkin the pcb?

Well, maybe I was a little exaggerating... :D the protection pcb under the positive pole still works if you can meassure a normal voltage level.

Negative side is really worse, in some cases the spot welding spots rip a hole when you tear the metal strip of. And underneath is bare battery chemistry... eBike batteries are even worse: Since they're made for higher currents, the stripes are much thicker and it's almost impossible to tear them of without damaging the battery. For those batteries, I use a Dremel to cut the stripes around the welding spots, that's much safer.

Have sun!
Oliver
 
daromer said:
They are welded like that to be able to handle the current. Generally in higher current applications you have a bit thicker nickel strips and you also weld it better.

The cells are cealed from start and on the positive side you have something called CID. This is a pressure switch you could say. When the pressure goes to high it will disconect the cell. This will for instance happen when the cell is put up for to much heat or to much current during a short circuit.

Imagine if you har torn a hole into the negative side... No pressure can be built up and therefore the CID will not work and stop above scenarios. Same goes if you destroy the positive side. You will then have altered or destroyd the function of the CID making the battery unsafe in events of issues.

Same goes with pressing the CID back with a screwdriver that some people do... This could potentially also make the CID useless.. And the CID did pop due to a reason :)

With this said you will not be able to get rid of the nickel strips on all types of packs and on some you are better of just cutting the strip and leaving the spot welded part.

I dont want to be a party pooper but on the same time i would personally never use a cell with above scenarios.... Atleast not in any application in a house or powering my house.. I though could use them for some toy outside but frankly.. How often do it happen? :) Throw them instead and you dont have to be in bed sleepless :)
I understand now :D

So if you look at the pictures I have attached, would you say these cells are no longer safe to use? Pictures 1 and 2 are from cells where I pushed the distorted positive pole back down and it then bent to the side. Picture 3, has a partly torn positive pole and its bent in a bit.
I have quite a few that are like this, most cells were only slightly distorted (1mm)on the positive side so im pretty sure they would be fine right.
owitte said:
The-J-Man said:
Wattsup said:
Sometimes those spot welds can be very solid.
Yeah no kidding :D
owitte said:
from my experience, a little distortion on the positive side doesn't really affect the battery's function or safety. Negative side is worse, since there's no space underneath the bottom plate. I'm using cells like this without problems, but you should inspect it carefully and check the protection PCB under the positive pole.

Well, maybe I was a little exaggerating... :D the protection pcb under the positive pole still works if you can meassure a normal voltage level.

Negative side is really worse, in some cases the spot welding spots rip a hole when you tear the metal strip of. And underneath is bare battery chemistry... eBike batteries are even worse: Since they're made for higher currents, the stripes are much thicker and it's almost impossible to tear them of without damaging the battery. For those batteries, I use a Dremel to cut the stripes around the welding spots, that's much safer.

Have sun!
Oliver

All my cells are testing and measuring just fine. thats a good sign then.
Yes exactly, its happened a few times to me, 20to be exact :(
have you not yet cut through the battery case with the dremel? seems like a high risk that you cut into the battery...

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There could easily be damage to the CID and venting mechanism. I wouldn't be surprised if the venting seal wasnt sealed anymore
Personally I don't use any power/rotary tools when disassembling packs
 
Scepterr said:
There could easily be damage to the CID and venting mechanism. I wouldn't be surprised if the venting seal wasnt sealed anymore
Personally I don't use any power/rotary tools when disassembling packs

Damn, these are (probably were)some fine cells. :mad:
If the venting seal has a leak, wouldn't I smell something or wouldn't some liquid come out?
 
The electrolyte only becomes "liquid" when it's hot. Which means the smell wouldn't come out till then as well. Kinda like plastic doesn't have a smell till it's about to catch fire. Soooo, you wouldn't know for sure till they were about to fail horribly. i wouldn't trust them either.
 
J-Man I'm actually interested in buying some PF cells, let me know if you wanna sell a chunk of cells, I'm willing to take them in whatever assembled shape they're in.
 
Korishan said:
The electrolyte only becomes "liquid" when it's hot. Which means the smell wouldn't come out till then as well. Kinda like plastic doesn't have a smell till it's about to catch fire. Soooo, you wouldn't know for sure till they were about to fail horribly. i wouldn't trust them either.

When I disassembled the ebike packs and ripped a hole in the bottom ones Iimmediatelysmelled it and usually instantly had the see through liquid come out. I heard a pfff aswell.

Scepterr said:
J-Man I'm actually interested in buying some PF cells, let me know if you wanna sell a chunk of cells, I'm willing to take them in whatever assembled shape they're in.

Good to know mate, I have about 100 PD and 30 PF. Where are you located?
 
I would assume the "pfff" was a spark, which instantly heated up the electrolyte in that spot, and the smell that followed. Kinda like a FLA when you pull the caps off. Normally, you won't smell the acid until it starts charging or there's a short.

But, if the liquid started coming out, I will say that it's probably a little more fluid than I thought. I wonder if the electrolyte gets less viscus after assembled and through use. I've watched a few youtube videos where they show the process of making the cells. In those videos, the electrolyte is sorta pasty as it's spread out on the sheets like butter.
 
The cells in normal state are dry. If they have been abused or heated before they may have pressure and liquid/smell to it...


I have opened both new and old cells and new cells have always been pressure less or very very close to it if you compare to old non functioning cells that can have severe pressure including the smell :D
 
I'm in NYC, I would take all the PF cells
 
The-J-Man said:
Scepterr said:
There could easily be damage to the CID and venting mechanism. I wouldn't be surprised if the venting seal wasnt sealed anymore
Personally I don't use any power/rotary tools when disassembling packs

Damn, these are (probably were)some fine cells. :mad:
If the venting seal has a leak, wouldn't I smell something or wouldn't some liquid come out?

It's not worth the risk of burning your house down. If you make a mistake, just throw them out. It's no big deal. It sucks wasting cells but we all make mistakes. I've ruined countless cells already. I throw them out as I don't want to risk one of them being damaged internally and causing a fire.
 
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