Li-Ion Thermal Runaway Question (nothing happened, just want to know)

As said in the title, nothing bad has happened, however, I feel I need to be prepared incase a 18650 "goes off" durring charging. Right now I always stay in the room while the batteries charge and glance at them every few minuites. I also touch them to make sure they are not hot and everything is working fine.

My question is how long would thermal runaway take if it occurs? Is it something I would catch by making sure the batteries are cold, or does it happen in a matter of seconds?

What should I do if a cells starts to vent? Right now I have an ammo box set up I could dump the cell into, however is this safe or should I invest in a class D fire extinguisher or am I just being paranoid because I have over 10 unprotected cells now...

The closest analogy would be that the cell would behave like a firework, with a bang and then shooting out flame for a few seconds.

You would get little or no warning of this, although the cell would have become very hot indeed beforehand. If you always stay with your cells during charging, you would notice this in time to stop the charge and prevent thermal runaway.

You would not be able to contain thermal runaway completely in a sealed ammo box, but if you left the lid weighted down, at least that should stop burning fragments flying around the room. Smoke/fumes would still get out. The smoke is toxic and you should be very careful to avoid inhaling it.

That is the slightly scary news. The good news is that you are obviously being careful and vigilant, so it is extremely unlikely that you will ever have a problem that gets out of hand.

I try to be very careful, as I have seen too many time on sites like Youtube 18650's exploding and it is not fun thinking that could be your house, car, etc. It is conforting hearing that the cells would have to take at least a minuite or two heating up first, as I have them right next to me at all times and touch them every few minuites to make sure everything is ok.

Would a class D fire extinguisher really be useful, as the explosion is only a few seconds, or is it something to have just incase the fire spreads to other cells?

What are the chances a cell in storage just spontaneously explodes for no reason at all, or is this like saying a gun "just went off for no reason"?

class D extinguishers isn't something you can buy in stores, as they are laboratory grade supplies

then where are the types of class Ds comes in
Type 1: The extinguishing agent for type 1 Class D is Sodium Chloride. The type 1 Class D extinguisher is effective at controlling magnesium, sodium, potassium, sodium potassium alloys, uranium, and powdered aluminum metal fires.
Type 2: The extinguishing agent for type 2 Class D is a copper based dry powder. The copper compounds smother the fire and provides an excellent heat sink for dissipating the heat of the fire.

type II is ridiculously more expensive than type I
http://www.thefirestore.com/store/p...medium=Google_Product_Search&utm_campaign=CSE

most cases reported on the forum has only a few seconds before the lithium chemical burns itself out, which by then the temperature would've ignited anything the cell may be sitting on so I think investing in a regular extinguisher would be enough

Personally I am against the use of unprotected cells as your risking more than you have to, but if you must use them check cell voltage every couple of minutes, especially after the cells are 90%+ [~4V]

I'm not sure what class D is, and it would be good if one of the firefighters on the board would weigh in here with some expertise and advice.

You would not be able to stop the runaway once it had started. My guess is that as long as the electricity supply was disconnected, water would be the best thing to use.

AFAIK there have been no reports of Li-Ion cells blowing up spontaneously. The most dangerous time for them is during recharging, and the danger is absolutely minimal if they are good quality cells which have been treated properly.

Thanks for clearing that up. Kinda wished it was something you could buy at BJ's, etc. but obviously someone didn't do their reading before posting I would probably not want to inhale bad fumes... just to put out other bad fumes...

DM51 said:

You would not be able to stop the runaway once it had started. .

Click to expand...

yup, rumble rumble, like a volcano is about to erupt, once that happens then within seconds. you get a warning it just isnt long enough to do anothing other than toss the grenade
you can Not start with it up on a desk/workbench and safely move it anywhere unless "FLINGING" counts
you have to start it somewhere safe. on some of the other tests that people did, they had 0 time, on impact or high input it just went off imediatally, but of course that is usually people TRYING to get it to happen.

if you put your eye out, it will cost more than the BB gun you got for xmas ya know.

dont forget you shouldnt charge them in the VERY very cold.

What would an example be of a "safe" place?

the bottom of a office type small metal garbage can with a loose top on it.
because they usually have that few inches of riser from the floor (no melted floor), the metal is thick enough to keep from burning through, and they are tall enough and large enough to allow for expansion of contents.
on the other hand, if they fill with gas, then it can blow the top off, which is better than splitting the sides.

hey at least its cheap.

and a weight holding the top like DM said, that worked for tests some people did.

I charge my cells in a battery clamp, with the whole thing sitting in a large pot. I keep it outside if possible (no rain), otherwise in the smaller of my two bathrooms (the one I don't care if I can't use due to burnt lithium crap everywhere ).

I never mistreat my cells, but since I'm in the habit of using old cells I am always careful.

I'm planning to build a fireproof sealed charging container, with a pipe I can run out of the window. Should a cell burst the noxious fumes will go through the pipe outside, and the burnt crap will remain in the container.

DM51 said:

I'm not sure what class D is, and it would be good if one of the firefighters on the board would weigh in here with some expertise and advice.

Click to expand...

read
http://www.ilpi.com/safety/extinguishers.html#Picking


personally I'd prefer buying a few beach pails and fill them up with sand...they have NO shelf life!, non compressed, and reuseable

That would be really cool, although charging outside is hard for me in northern NJ... I really like your idea though, as venting the fumes away would be the biggest problem for me.

some vids, i am looking for the ammo box explosion, but might as well list the ones i find. remember these people are usually trying hard to do this, and some are being really stupid.

Li_poly
http://youtube.com/watch?v=k5f0VCoFuFM
http://youtube.com/watch?v=z3o_2mwRPdw
http://youtube.com/watch?v=odxR1lkfiEI
http://youtube.com/watch?v=pAEe0QO6TMU
http://youtube.com/watch?v=sNeeIzaeYDo
http://youtube.com/watch?v=FaB2cZEcYXI
http://youtube.com/watch?v=ZNxLGDwGw-k
http://youtube.com/watch?v=RQjudHKh-bI
http://youtube.com/watch?v=KpUXuEg3fNE
http://youtube.com/watch?v=n0M-ZX2DBxY
http://youtube.com/watch?v=0MiM2E6pvfg

post somones loss on workbench
http://youtube.com/watch?v=n0M-ZX2DBxY

battery bunker
http://mysite.verizon.net/kevinkel/index.html
pottery can be cracked with can cells

liposack
http://www.liposack.com/

vented cashbox
http://www.rcgroups.com/forums/attachment.php?attachmentid=372891
still cetches things on fire

-----------------------------------------

li-ion canned
http://youtube.com/watch?v=WeWq6rWzChw
(laptop)

123
http://youtube.com/watch?v=A9ayuFBDrSg

water test
http://youtube.com/watch?v=v7abq34mckg

both
http://youtube.com/watch?v=m2cg4mdN2pU

setting a bad example :-(

remember cans can have shrapnel, explode faster, as opposed to poof, and because of protection ON cans , andode disconnect, its harder to force it to happen, so that is why you see less of it. but a Cheap one without annode disconnect, becomse a pipe bomb too, with the metal can you can get more "rocket" occuring.

anyways everyone is different, and unpredictable, but with some visuals, you can get an idea of what your going up against.