Wow these must be grade A cells how much to buy them after they pass your torture test. Iâd love to strap that ultrafire to my head in my armytekâŚâŚ :person_facepalming: 
indeed. i will be testing to vent them later today using a blow torch remotely.
Crushing the 25R probably breaches the containment membrane that keeps the two reactant chemicals separate.
The eventual failure of that membrane from slow crystal growth that pokes a hole in it is the problem described as leading to failure with venting and generation of heat, and the chemicals used are flammable.
The eventual failure is described as happening from heat cycling and age, and as a problem with counterfeit cells or cells made in dirty conditions with metal fragments that cause a variety of problems inside the cell over time.
If you look up âaccelerated agingâ as a test procedure for li-ions, youâll find various descriptions.
The membrane separator, if well made of the proper material, isnât likely to fail quickly solely from external heat being applied, and if the liquid inside boils off through a proper vent releiving internal pressure, into an external fire, it will just burn off (though you probably donât want to breathe downwind.
Part of the question is that there as yet no standards for producing li-ions, so you rarely know what you get or whether it has been tested. The brand name cells have gone through the accelerated aging/cycling tests and theyâre careful about manufacturing to specification without corner-cutting, for that reason.
Have you weighed the cells before and after heating them, to determine whether theyâve lost any of the contents through proper controlled venting when heated?
UPDATES! - July,4th,2016
Successfully got some 18650âs to vent, by applying heat from a propane torch remotely. after two vents, i successfully got a cell to vent inside a flashlight! The light was a metal tactical design, but with a side clickie switch. it melted the switch, then vented enough to blow the driver, reflector, and LEDs out the front. I captured the tests on video. as soon as i return from my holidays i will upload the videos of the tests. I also tested a AAA Alkaline and a AA Zinc Carbon with the heat test.
Lol!!
NO! Post it now!! 
Were the flashlights turned on when they exploded or no?
Canât wait to see the videos!!!
yep, it was turned on. its in the video where it goes out roughly 5 minutes before the cell vents in the light.
CoolâŚâŚthis should be classic!
Iâm interested in this. I also want make tests like that. I made a polycarbonate box for my phone to take 720p 120 fps videos from some exploding things at a very close distance
Looking forward to the video.
Well crap⌠Now I donât know what to do. You guys talked me out of making the 18650 golf ball cannon, because li-ions just wonât vent with force⌠But now they do???
I cannot wait to see the videos. Thank you my friend to the north.
from my tests LiIon cells vent more like a model rocket motor (or a small fireworks fountain) outside of a flashlight or unsealed battery holder.
inside a sealed flashlight body its a different story.
From our observations the plastic switch assembly or plastic lens/reflector in cheaper lights will blow out releasing the pressure before they can build up enough pressure to explode the metal body like a metal pipebomb. in a stronger more sealed light, substantial pressure could build up before the tail cap, switch spring metal plate, or driver/star/reflector/lens would fail causing a âburstâ explosion sending some shrapnel out with force.
even in the cheaper light i tested, the plastic side switch & rubber cap blew out with some force ejecting parts, (to fast for the cameras to see) and knocked over the holding jig we built to hold the light from jetting away like a rocket.
This sounds like so much fun I canât wait to see the videos.
Your results with 12V charging are not that surprising. It is very similar to some tests the manufacturers do, except theirs last hours.
I had a 18650 cell vent in a Convoy C8 yesterday as my car burned up. There was enough force to eject it from a closed center console to just outside of the open car door. Will try to get vids or pics from family who were there- I have none myself. Was similar to vidâs Iâve seen with sparks ejecting etc. for about 4 seconds.
Looking forward to your Vids DBSAR
Phil
SawMaster did the cell cause the car fire or vice versa? Hate to hear that your car burned up!
Itâs been awfully hot here in SC, I thought I was going to spontaneously combust while doing yardwork today.
The car was the fire, not the cell. In thinking it all over Iâm sure the console acted to insulate the light somewhat as the plastic would have had to burn away from the light (ablation) to expose its aluminum body directly to the full heat of the fire. There was also a full BIC butane lighter in there which vented rather than exploding, and IIRC that was about 1 minute after the interior began burning. I found that unusual having seen the results of lighters being tossed into fires where they have always exploded. Thus I believe the temperature rise in the console was slower than where there was direct exposure to the flames. It was still hot there from about 1 minute on though, well above the temps any car would see from anything less than a fire which I feel indicates that it is safe to have a LiIon light stored in your car. The biggest loss was that it also burned a small part of a Bermuda grass yard which cost $375 to have new sod put in to repair it. Without insurance that is out-of-pocket. The shell of the car was scrapped netting $180 for the salvagers who I gave the remains to. Could have been a whole lot worse. Pic is from after getting the car towed home. The only remaining plastic was at the very back, everything forward including aluminum was melted and gone
(canât figure out how to post pic so follow link HERE[user]=145398863&filters[recent]=1&sort=1&o=0
Phil
go to the source, right-click and choose to copy the image location/URL
click the little âsunsetâ icon above the Comment box here
paste
put something in the size box like â50â
preview
adjust the number for âwidthâ in the raw html you see in the editing window during preview, e.g. !{width:30% âŚ
optionally go back to where you got the picture and copy the URL from the web navigation box at top of web page
I especially liked the Photobucket offer to make you up âHappy Holidayâ cards featuring your chosen image.
I laughed pretty good at that!
Seconded