Why did the battery become volatile?

[Semiretired]

A little background first. I use joyetech Evics with both an 18650 Tube and an 18350 Tube. I have both tubes so I can switch to a shorter version when I go somewhere. These tubes have a metallic spring bottom and the top has a plastic cover to retain the battery in the tube. I generally carry around the short tube and switch it out when I need to reduce the form factor. I have been doing this for over a year now. I have 8 18650s and 4 18350s that I rotate through. The 18350s get rotated the least since they are only used when I want to reduce the form factor.

The other day I was headed out so I grabbed the short tube and put a new battery in it since the other one had been used a few times and I was not sure how much life was left in it and headed out the door. I was carrying the short tube in my pocket (there was nothing else in my pocket with the tube). While I was driving down the road to my destination the tube started getting hot (I mean real hot). I pulled it out of my pocket and I could tell that the heat was building tremendously so seeing an empty lot next to where I was driving - I threw the entire thing out the window. I was not going to take the chance or the time to figure out what was going on.

What I would like to know is what could have made it go volatile? The battery was not newly charged. It was not connected to a PV and there was nothing else in my pocket that could of caused a short connection. Oh and to add. It had already been about 3 hours since I had left the house since I was on a long drive so if something was wrong with the tube or the batt (internal short or something) = shouldn't it of gone volatile sooner.

Might be thinking this out to simply, but this has me dumbfounded as to what could have been the cause of the problem.

 

[Semiretired]

Did I post this in the wrong forum?

 

[Tnumbers]

in theory, if it was a already a bad cell, it could have been set off from the heat in your pocket. It would have taken it a while to heat to body temperature all the way through. And as i said, it would have had to have already been a bad cell. But thats all i can think of. Or if there was metal in your pocket, there is a section of the battery, where if the wrap on the battery were cut and the metal were to touch both places it would heat quickly.

On a side note, if it was an external short it would have cooled off instead of venting, and could have been thrown away properly later. Though i dont blame you for throwing it out your window.

 

[Switched]

Carrying a spare battery in a metal container is a no no and an accident waiting to happen, that is why spare battery carriers are designed and fitted plastic. As the previous post stated there was something wrong with the insulation of the battery. Of course this is all speculation, but batteries do not go ballistic for no reason.

 

[mogium]

More then likely it was just firing in your pocket never keep them in your pockets while driving

 

[Switched]

More then likely it was just firing in your pocket never keep them in your pockets while driving

THere was no head attached, he carried it in a spare 18350 eVic tube.

 

[edyle]

THere was no head attached, he carried it in a spare 18350 eVic tube.

oooh; now I see; it was in a spare evic extension tube with a plastic cover;

so what happened the positive end of the battery was pointed down to the spring, and the insulation on the side of the battery had a tear, and that's how it shorted.

the plastic end was on the negative side; if he'd put it in the other way the short would not have happened.

 

[Semiretired]

I am sure that the battery was not in upside down. When I glanced at it before I threw it out I checked that. If it had been in upside down I would have just unscrewed it and been done with it, but in the brief moment that I took to look at it - I could not see anything that looked obvious - so out the window it went. I just could not think of any reason it was going south - so I tossed it for safety.

After thinking about it for a while - the only thing that I can think of is that somehow I scratched the cover while inserting it into the tube - possibly a bur had formed on the threads and that is what caused the problem... I check my battery covers prior to ever recharge and I never use a freshly recharged battery, so I know the cover was in tact when I inserted it. I have now added check the threads to my check list. Thanks for the thoughts, but I am still unsure of what set it off - beyond the possibility of the bur or possibly the cell going bad...