Post #37 in topic “EXPLOSIÓN PILAS 18650” @ForoLinternas
jomertab reports:
Ashes all over the room reported.
That cell may have been left too much time over-discharged, I presume.
Cheers ^:)
Man, I can’t wait for lithium ion cells to be as obsolete as VHS…
Charging 4 GAs as I read this… 4.04V at this moment using VP4. Just checked temperature per cell… Hold on let me check again…
+1 Here it is! Idiots gonna be idiots! :person_facepalming:
It doesn’t sound very nice, but a guy at work likes to say, when somebody is being unbelievably idiotic, that in the wild they would have been food.
hardly an explosion
Seems strange to blame the battery, I’d blame the human who was stupid enough to charge a cell in that condition at 2 amps.
Bit like someone checking their gas tank has fuel in it with a cigarette lighter, then blaming the gasoline when they blow half their face off 
I agree, I hate charging perfect condition cells at 2 amps, I generally charge them at .5-1 amps tops. I see no reason to stress them out while charging them unless I am in a hurry. In that case I keep spare cells around for a reason.
When reviving a battery in particular though I will at most do 500ma, generally less all the way to 4.2V. Then rest the cell for a week or 2 to see if it maintains the charge before using it.
Any cell that doesn’t maintain at least 4.15v. Dropping from 4.2 to 4.15 is fairly normal after resting but much more is a no go for me unless used in a very low drain application.
I dont mind the jump starting so much (but with cells so cheap why), but here is the first indication of an issue:
“After 3 hours of slow recovery to 3V”
If it takes 3 hours to come up to 3v something is very very wrong!
That^
If I tap a dead cell with a charged cell it will generally recover to ~2.5V or so almost instantly.
It will then charge to ~3.2V within a few minutes before slowing down for the “real charge”
Wow, impressive sounding explosion.
At over discharged voltages the copper current collector can dissolve in the electrolyte. Then when the cell is charged the copper re deposits and can form dendrites and cause a short.
Fellows, jomertab wasn't overly prodigal on providing precise information as to what exactly he did and how. I presume he just gave the cell some very brief bursts to raise it to “some” voltage, and then he set it on the charger. I don't know what minimum voltage is required for a BT-C3100 to pump some sort of charge current for a presumed li-ion cell, probably slightly more than the maximum typical value for a Ni-MH; for the same reason, I also don't know what current does it pumps in such a case, yet my guess is “quite low”.
Unless someone can provide with some sort of wise information in this regard, I see no point in those “raise slowly” policies. Little energy is actually required to set the cell in “valid” (2.5+V) territory, so if you're willing to take the risk in recovering a cell, which can be pretty 0K if over-discharged for just a brief while, I'd just give it some little low duty cycle bursts from another cell for it to get into charger acceptable voltage territory. Or use some sort of slow, dumb chinese charger… and take cover! That's about it. :-)
Cheers ^:)
sounds like he spun the cylinder one time too many…
probably a worn out junk cell that had high resistance and damage from overdischarge pushed into thermal runaway by a too high charge rate for even a new cell of that type.
i/o error.
means idiot operator.
I doubt charging at 2A could cause enough heating to cause thermal runaway.
My explanation above about re-depositing Cu seems more likely.
Barkuti, Did he say how long the cell was left over discharged?
Cheers ^:)
read it again.
2a rate AND a damaged cell.
Reading the link posted in the OP indicates that the cell was a Panasonic NCR18650 so a quality cell but I couldn’t see anywhere if it was protected or unprotected. Raising the voltage of a tripped protected cell is ok but if it was unprotected with zero voltage then trying to charge it up is in my opinion only asking for bad things to happen.
It reminds me of a coworker who used to reload 9mm by dipping the cases into powder until they were full to the brim. When I asked what powder it was he said he didn’t know and why that would matter.
Both are operator issues in my mind.
yep equally foolish or more so.
some powders it wont perform and others will result in shrapnel of the firearm in your face.
It looks like a tear-down rather than an explosion…