One of my cells exploded...

M

Mark Lex

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Jun 25, 2017
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Sharing my experience of what happened yesterday, maybe someone can offer an explanation?

I'm sitting down when I hear a loud bang (like a cap gun going off) coming from the direction of my charging station. Scared the sh!& out of me. I jumped up and looked over, everything looked fine, cells in the charger were not hot, charger still happily working...
I was not able to find the cause of the noise until this morning. I found a white ring on the floor, from one of my cell tops. Sure enough, one of my cells (near the charger) was missing its top and the sleeve top was also ripped open. This cell had come from a Bosch drill pack, it had not been charged or discharged, but it had been freed from its pack and had been sitting for 4 days, waiting to be tested. You can see in the photo where the CID? is now pushed up to the underside of the positive terminal.

Is there an explanation for what happened? And can something like this be mitigated?

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MarkLex said:
Sharing my experience of what happened yesterday, maybe someone can offer an explanation?

I'm sitting down when I hear a load bang (like a cap gun going off) coming from the direction of my charging station. Scared the sh!& out of me. I jumped up and looked over, everything looked fine, cells in the charger were not hot, charger still happily working...
I was not able to find the cause of the noise until this morning. I found a white ring on the floor, from one of my cell tops. Sure enough, one of my cells (near the charger) was missing its top and the sleeve top was also ripped open. This cell had come from a Bosch drill pack, it had not been charged or discharged, but it had been freed from its pack and had been sitting for 4 days, waiting to be tested. You can see in the photo where the CID? is now pushed up to the underside of the positive terminal.

Is there an explanation for what happened? And can something like this be mitigated?
Click to expand...

There are several reasons why this may have happened. Being a drill battery, it could have been dropped and damaged internally. It may have been overcharged, how did you charge it?
 
Dang, and you didn't get a video of it :p

Seriously, though. Glad you're ok and wasn't anything really spectacular. It could of been worse. Like a roman candle went off.
 
Amazing and very wierd, another one just exploded, from the same pack.

I did not charge it, nor did I discharge it. The only thing I did was free the cells from the drill pack. They are waiting to be tested. Dunno if it matters, but I have stored them vertically.

No damage done, but I'd like to find an explanation for it.
 
I'd not trust any of those cells at this point. 2 popped cells within 24 hrs from the same pack. To close for my likes. I'd toss all those :-/
 
Already isolated and quarantined.
Pics of the second one that exploded.
AND... after removing all 10 cells that came from this pack, I discovered a 3rd cell with its ring blown off!
Any theories?

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MarkLex said:
Already isolated and quarantined.
Pics of the second one that exploded.
AND... after removing all 10 cells that came from this pack, I discovered a 3rd cell with its ring blown off!
Any theories?
Click to expand...

Wow. That's crazy. No theories here. I am curious as to how long the pack sat before you opened it. Maybe check the voltage on one that hasn't exploded (if your brave enough).
 
can't say for how long they've been sitting. I liberated the cells about 5 days ago now, and they've been sitting ever since.
#1. (popped) 1.04V
#2. (popped) 1.19V
#3. (popped) 0.40V
#4. 2.58V
#5. 2.83V
#6. 1.10V
The last 4 cells behave strangely when I try and measure their voltage, they start at just under 1.0 V, the longer I hold the probes on, the more the voltage drops, and then stabilises around 0.1V. This takes about 5 - 8 seconds. Varying the pressure of the probes also gives different results.
#7. 0.1-0.9V
#8. 0.1-0.9V
#9. 0.1-0.9V
#10 0.1-0.9V
These are definitely NOT going in the powerwall.
 
When you removed it did you perhaps destroy the top end? Ie shorted where the cid is? If so this short will generate gas in the end when they become warm and if the cid protection does no work any more it will just go boom

Just a theory :)
 
I'm sure the BOSCH drill was from the green series, made for home users. If you want cells that work, take the blue series by BOSCH. These devices are made for professionals like us :D .

No, seriously, I also experienced cells that had a wild 'voltage jumping' when I tried to measure them. My advice: Put them all in a bucket of water, far away from you and your family. Or use a portable safe to bring them to the recylcer... ;)
 
MarkLex said:
...
when I try and measure their voltage, they start at just under 1.0 V, the longer I hold the probes on, the more the voltage drops
...
Click to expand...

Could be the input impedance of your multimeter dragging the voltage down?
Most meters have very high impedance but with those cells having~zero chargeeven a draw in thepico-amps could be enough to see the voltage sag.
 
owitte said:
I'm sure the BOSCH drill was from the green series, made for home users. If you want cells that work, take the blue series by BOSCH. These devices are made for professionals like us :D ....
Click to expand...

When I went to update my cell spreadsheet, I realised I made an error. :blush: They actually came from a RYOBI drill pack, not BOSCH. Apologies for that bit of misleading info.
UPDATE: no other cells have popped...yet, but I am monitoring them closely. Those LG cells are rated at 1500mAh, so would never have made it into the powerwall anyway, as they are below my cutoff.
 
I know why. I had one do the same. Didn't explode thankfully. Corrosion shorted it out. I pulled it out of the holder and it started smoking. On examination the others are corroded around the top. No, I'm not game to take a photo. Water damage is dangerous
 
A fourth one has now popped. That's 4 cells out of a 10 cell pack that have displayed this behavior.
If it has something to do with the way I break open the pack, then surely other cells would also display this behavior? Don't thing it is, as I take my time when breaking open the cells now. Earlier, in my haste, I shorted a few cells by accident, now I'm more careful.
I'm slowly coming to the conclusion that this particular pack was abused/mistreated before I got it.
 
Yeah, I'd say it was a problem with that pack. I could of been regularly drained to death and then charged and reused continuously. That's a guess, tho. Who knows how many cycles they've been through, too.
 
This is normal behaviour of a 18650. Month ago I found it a good idea to discharge the cells I want to through away down to zero volt for saftey reasons. This is not a good idea as I found out. They get very hot doing this and some of them did blow. Not as dramatic but I could hear gas escapeing. I guess with the low cell voltage the cell chemistry goes to hell and reacts accordingly.
 
Herbi said:
...
This is not a good idea as I found out. They get very hot doing this and some of them did blow. Not as dramatic but I could hear gas escapeing. I guess with the low cell voltage the cell chemistry goes to hell and reacts accordingly.
Click to expand...

Hence whythe cell manufacturers use terms like'keep out' (Sony)and 'unstable region' (Panasonic) etc etc


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Sony Technical Handbook

Panasonic Technical Handbook
 
Lithium like all battery's have a bounce back if they are not bad. My theory is like the ones i have seen you pulled them from a pack where the circuit protection was keeping the lithium out of breakdown. when you pulled them they no longer in the circuit so all they had was internal resistance and started to try to rise in voltage as the lithium has started to breakdown till the breakdown gasses pressurized the casing and popped. ive seen this before if i get time ill try to see if i can reproduce with some of the 500ma cells i have. i would have to bet if you were to charge these they probably would have ended up getting hot till they burst in flames. Any cells i have below 2v i normally charge them at 20 ma with a CLD on a 3.3v rail from a cpu psu. inside a metal enclosure on my concrete floor. so they may or may not burst in flames. if they dont then i will let them sit for a week and see if they self discharge before attempting to charge to capacity. Just be safe lithium is dangerous which all you guys probably know=P
 
Update: 7 cells have now exploded. only 3 cells of the original 10 are still intact.
Some interesting theories posted...
I'm not game to attempt charging the remaining 3 cells.
 
That's just crazy! I don't blame ya on the charging of the last 3. Although, could make for some interesting video ;) If you do this, just make sure it's outside well away from anything flammable.
 
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