Should I replace a bent cell?

endrew

10 W
Joined
Apr 7, 2018
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92
I dropped my battery like an idiot, and one of the cells got bent. Is this dangerous? Should I replace the cell?
 

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Yes, and now rather than later - no idea of that cell is a time bomb or totally fine after that kind of damage.
 
endrew said:
I dropped my battery like an idiot, and one of the cells got bent. Is this dangerous? Should I replace the cell?
Is he serious or just kidding ... maybe both :thumb:

Possibly his first spot-welded DIY build ... possibly not even had its first c/d cycle test - yet.

Luckily the pack wasn't fully charged AND today's cylindrical cells now have positive temperature coefficient thermistors, positive temperature coefficient electrodes, current interrupt devices, safety vents, protection circuitry, shutdown separators, electrolyte additives, safe electrolytes to prevent thermal runaway. Even so Lions' are not idiot proof.

An accident like what happened with endrew usually is due to "haste makes waste" when we least expect it (Murphy's Law). Like with a mindset of driving defensively - DIY pack building should also be done with a defensive mindset.

Maybe, this mishap will be the best lesson endrew ever learned about DIY projects being potentially dangerous. We all can learn from the mistakes of others; ESPECIALLY when it comes to DIY battery builds.
 
endrew said:
I dropped my battery like an idiot, and one of the cells got bent. Is this dangerous? Should I replace the cell?
That is not “bent” ,..it is severly damaged and consequently a major risk of failure and fire.
Fix it ASAP !...and in the meantime, put that pack somewhere safely out of range of any flamable property or materials.!
 
Thanks everybody, the cell was dismantled and discahrged. Just making sure, you wrote its not "slightly bent", see attached images, do you consider this "severly damaged"?
 

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Yes :roll:
The cell is filled with a tigthly packed roll of thin cathode/separator/anode/separator sheets. A dent like that will inevitably put pressure on the roll with possible tearing and puncture of the separator sheets with risks for short circuits as result
 
endrew said:
Thanks everybody, the cell was dismantled and discahrged. Just making sure, you wrote its not "slightly bent", see attached images, do you consider this "severly damaged"?
You should have said "dent" instead of "bent" according to your two photos. With the side "dent" so severe as to expose air/moisture to the inside.

Looks like you applied an epoxy sealer over the severe indentation on the side of the cell that's visible in the lower photo.

You purposely turned the cell in the top photo so as not to expose the severe side indentation. By doing so did you actually think someone might miss that severe side indentation and say, "If it still tests OK ... " :roll:

It has us all shaking our head that you even have to ask ... "Should I replace a bent cell?" You purposely held the cell (top photo) as if the only damage was the dent on the end of the cell.
endrew said:
... see attached images, do you consider this "severly damaged"?
Are you referring only to the end dent? :roll:
 
I think what you are referring to as the "side dent" is in fact a layer of protective material lapped onto the cell, and not the cell itself.
 
I personally wouldn't trust that cell either.
 
I've seen a dent like that cause an internal short and made the cell go off immediately. Like a little rocket motor. If the cell didn't go off, it was likely on the verge of it. Good idea to totally discharge it. I think you got lucky this time.
 
Chalo said:
I think what you are referring to as the "side dent" is in fact a layer of protective material lapped onto the cell, and not the cell itself.

Exactly
 
eMark said:
endrew said:
Thanks everybody, the cell was dismantled and discahrged. Just making sure, you wrote its not "slightly bent", see attached images, do you consider this "severly damaged"?
You should have said "dent" instead of "bent" according to your two photos. With the side "dent" so severe as to expose air/moisture to the inside.

Looks like you applied an epoxy sealer over the severe indentation on the side of the cell that's visible in the lower photo.

You purposely turned the cell in the top photo so as not to expose the severe side indentation. By doing so did you actually think someone might miss that severe side indentation and say, "If it still tests OK ... " :roll:

It has us all shaking our head that you even have to ask ... "Should I replace a bent cell?" You purposely held the cell (top photo) as if the only damage was the dent on the end of the cell.
endrew said:
... see attached images, do you consider this "severly damaged"?
Are you referring only to the end dent? :roll:

Dude... You've got issues... Why would I ask a question and try to deceive you? the wrapping of the cell was not broken. As mentioned above, on the side of the cell is a layer of protection glued with hot glue to the row of cells.
 
eMark said:
endrew said:
Thanks everybody, the cell was dismantled and discahrged. Just making sure, you wrote its not "slightly bent", see attached images, do you consider this "severly damaged"?
You should have said "dent" instead of "bent" according to your two photos. With the side "dent" so severe as to expose air/moisture to the inside.

Looks like you applied an epoxy sealer over the severe indentation on the side of the cell that's visible in the lower photo.

You purposely turned the cell in the top photo so as not to expose the severe side indentation. By doing so did you actually think someone might miss that severe side indentation and say, "If it still tests OK ... " :roll:

It has us all shaking our head that you even have to ask ... "Should I replace a bent cell?" You purposely held the cell (top photo) as if the only damage was the dent on the end of the cell.
endrew said:
... see attached images, do you consider this "severly damaged"?
Are you referring only to the end dent? :roll:

You can see in this picture I sis not intentionally "turned the cell in the top photo so as not to expose" anything...
 

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From the first photo you posted using the word "bent" thought you were also referring to what looks like the sheen of epoxy glue sealer. Looks like some side dent damage to the can that broke open the shrink wrap. As it's more noticeable in this photo than a shoulder dent.

Thanks for clarifying with above photo as apparently there was no side damage to the can.

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Always a good idea to purchase a few more cells than needed for a DIY build just in case of an accident. Always remove any damaged cell as well as suspect damage to adjacent cells.

Better to be Safe than Sorry :flame:
 
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