Lithium Ion Battery Explosions and pressure release vents.

[shining]

Hi, I'm rather a noob here, sure this was beaten to death but I could not find the answers. Any links would be welcome.

I decided to buy a Zebralight H60 headlamp working on 18650 battery and thinking if a battery with a pressure release, like AWs, is good or bad. My reasoning why it's bad is that since H60 is very airtight and its body is thicker than the battery's if there is a slow pressure buildup in the battery which causes it to rupture, it will not be enough to tear down the light. To the contrary, with the vent in the battery huge pressure buildup can go unnoticed eventually causing the light itself to rupture with far worse consequences... If the pressure build up is instaneous, AKA explosion (hope that this is unlikely while strapped to my head), this vent will not help at all. So I think just protected Trustfires would be safer than AW's with the vent... Am I wrong?

 

[hopkins]

Think is was just the one time use Lithium batteries that have
'vented with flame'. Called Lithium Primary cells. Different chemistry than rechargeable lith-ions.

If your rechargeable 18650 cell has a built in protection
circuit thats about as safe as your going to get.

Oops - forgot about the Sony notebook battery recal. (youtube notebook battery fires)
And all those were 18650 cells...hmmm... in packs. faulty recharging circuits? or bad batteries? both? don't know!

I've posted the need for a vent hole in flashlights that use primary lithium cells as they
have exploded with enough force to injure.

 

[Mr Happy]

The Sony notebook battery problems were caused by a manufacturing fault that short circuited the cells upstream of the protection devices. Under those circumstances the cells get extremely hot and burst venting flammable vapors. When exposed to air these ignite and produce hot flames.

There is an very low probability of this happening to good quality Li-ion batteries, but it can't be ruled out entirely. For absolute safety, you never want to be wearing a Li-ion cell or battery close to your body. In the case of cell phones of course this protocol is universally disregarded, but reports do exist of injuries from exploding cell phone batteries.

You have to make a choice about what you are comfortable with. The risk is extremely low, but not zero.

 

[StarHalo]

I know of at least two CPFers who've been injured by primary lithium battery "events", but none who've had any such issues with li-ions. I'd say you're safer with li-ions than primaries. And always get protected cells.

 

[shining]

I know that the chance of explosion is low - this is why I ordered a headlamp powered by 18650 battery. The question is about the utility (or additional danger) of the battery's mechanical protection features like pressure vent in an airtight light.

 

[Mr Happy]

I don't know anything about pressure vents. Do you have a link to a description?

As far as I know, Li-ion cells are made in big factories to generally standard designs. What I believe AW does is source good quality cells from a major manufacturer and then fits them with his protection circuit.

I would say your worries about mechanical pressure vents are unfounded. If a Li-ion cell should happen to fail in a bad way while inside a light, the light will explode. At best the emitter assembly will be blown out the front and the energy will be directed forwards. At worst you will have major burns to your head.

If a cell is working normally there is no gradual or slow venting. The cell is either tightly sealed with no venting at all, or it is failing with a big eruption imminent.

 

[shining]

From AW's thread at the Marketplace:
***All the above protected cells have Anti-explosion Vent / PTC ( mechanical thermal protection ) in addition to the electronic PCB protection.

I don't know anything about pressure vents. Do you have a link to a description?

As far as I know, Li-ion cells are made in big factories to generally standard designs. What I believe AW does is source good quality cells from a major manufacturer and then fits them with his protection circuit.

I would say your worries about mechanical pressure vents are unfounded. If a Li-ion cell should happen to fail in a bad way while inside a light, the light will explode. At best the emitter assembly will be blown out the front and the energy will be directed forwards. At worst you will have major burns to your head.

If a cell is working normally there is no gradual or slow venting. The cell is either tightly sealed with no venting at all, or it is failing with a big eruption imminent.

 

[csshih]

I"m using sony and samsung unprotected 18650s..
I abuse them allot and none of them have done anything.

I thought that AW's cells had an additional protection, that when they started venting,

well, on the RCR123A thread

New Anti-expolsion Vent/PTC Module : the new module provides an added layer of protection against gas built-up in addition to the PTC thermal protection. Unlike regular vents used by most LiIon cells, these new modules will actually stop the action by separating the electrodes inside the battery when the pressure reaches a preset threshold. The vent disc will open and release the gas plus stopping the cell from further chemical reaction. Combined with the PCB electronic protection and two layers of mechanical ( thermal and pressure ) protection, these new protected R123s are the first with these added safey features in place.

And I guess that includes other cells, 18650..

 

[Mr Happy]

Well that mechanical vent information is interesting. Maybe it reduces the risk further than older designs of cells in that case.

 

[hopkins]

a vent hole in the flashlight tube could save the emitter/reflector assembly from being blown out the front and thus save the light from any real damage.


A small hole plugged with candle wax which would soften
from the heat and be expelled from the pressure of a lithium cells venting
hot gas seems a good idea.
The best place to drill the hole in the tube would be...?

 

[mdocod]

I have only read 1 report of exploding li-ion cells on this forum that did not take place while the batteries were charging. The only reports I have read of explosions while they were charging were caused by user error during charging. The exploding li-ion cells in a flashlight was in a 4xRCR123 powered cheapo light, being powered by 4 unprotected cheapo RCR123s from a less than reputable source.

Use a Pila IBC and AW cells and you shouldn't have anything to worry about. The chance of explosion while the light is on your head is remarkably low.

Eric

 

[shining]

I got it: AW's vent not just prevents pressure buildup in the battery, it also disconnects the circuit. I thought it was similar to my eneloop's "vents" - found recently my Fenix L2D with the rubber button sticking out due to the offgassing caused by one cell being reverse charged by another while the light was still on.

 

[Burgess]

_

 

[snakebite]

the sony cells that were recalled had gotten contaminated with tiny bits of metal as they were made.
if these bits cut through the seperator and cause a short that cell will vent with flame/explode/vent,ect.
since these cells were in a bundle with others the heat from one going off will quickly involve the others causing a chain reaction.
in a single cell light this danger does not exist.
and if the cell in your light goes like this while you are using it you will likely notice loss of output.when you go to open it to change battery you should notice the heat.
as was mentioned earlier 99.99% of this failure type happens while charging.

 

[linterno]

I have only read 1 report of exploding li-ion cells on this forum that did not take place while the batteries were charging. The only reports I have read of explosions while they were charging were caused by user error during charging. The exploding li-ion cells in a flashlight was in a 4xRCR123 powered cheapo light, being powered by 4 unprotected cheapo RCR123s from a less than reputable source.

I have read much about cheap Li-Ion batteries explosion, but I have never seen the first. Do you have the reference to that report?

EDITED:

After reading a lot of threads and getting some replies from Tom (SilverFox) I would say that, even if I have a couple of ultrafire and a couple of trustfire batteries and I have not had any issue (yet and hope I will never have one), these are very inconsistent batteries and must be used very carefully. I you can afford them better buy AW batteries. I you are rich then buy Pila.

- Don't buy Ultrafire/TrustFire (any cheap chinese Li-Ion batteries) if you don't own an accurate multimeter to test their voltage before, during and after charge/use.
- Preferably, don't use then in series unless you know exactly what you are doing and could happen.
- If you can afford it, buy a good charger. At least a Pila IBC (~$45 including shipping).
- When charging, if the battery gets hot then stop charging immediately.
- If you find an inconsistent battery stop using it.
- Li-Ion batteries can be very dangerous.
- If you want to remove the protection circuit from those non working batteries, please be cafeful, you could short circuit the batteries and if you do it for a prolonged time the battery could vent causing fire and burning your hand, or even worst, your face.

Probably I don't like the words used by some members here when talking about those cheap UltraFire/Trustfire/(x)Fire, but I must accept that their use can be dangerous.

Respectfully,

Juan C.

 

[CELICA XX]

I just got a Surefire G3L-F

Are these battery vents on the tail-cap ?

 

[csshih]

I believe that's just the retaining ring for keeping the tailcap clicky in place but I might be mistaken.

 

[65535]

I for one would not buy a light with a hole in it, for hopefully obvious reasons.

If the cells vents it's going to damage the light regardless of a hole. The gasses that escape the cell take electrolytic gel and solids with them and deposit it throughout the available space.

The safety vent on AW cells is to make sure they don't blow up when charging, rather just safely vent. In a light pressure will build up if something vents, but it would take a catastrophic failure to be at all dangerous, where the cell completely vents.

As for the SF above, not that is a screw in ring with holes to fit the tool that is used to torque the ring down.

 

[VidPro]

the vent on Li-Ion does an anode disconnect. so if a short existed, AND gas buildup was the result , the battery would disconnect.
it IS dependant on the exterior being at one atmosphere to work properly.

the biggest problem comes when charging ANYWAY, when a gassing would cause the anode disconnect to disconnect the charge, Permenantly, which will stop the power from going in, which could stop the thermal condition.

The biggest problem with a sealed light tube, is the ones with multi seals, and long length seal, that act like a Tire pump when you screw them down, which can add pressure around a seal that is designed to differentiate between internal cell gas pressure and external air pressure..

if the anode does not disconnect because a pressure releace Can Not occur, because the containment around the cell keeps the pressure differential from exisiting, then the cell can potentially continue into a full runaway when there is a slight possibility that a disconnect of the anode would have stopped the continuation.

so the OPs question isnt wildly off, you wouldnt put a cap on a pressure cookers purposfull releace item. and in many li-ion specs it says not to do that.
in this situation not only could it releace pressure but its design STOPS the connection in a vain attempt to stop the problem that caused the gassing.

all the lights I Charge li-ion in, are not sealed, and many lights are waterproof (still) without being Pumps and rock solid seals, you can see that when the button rubber balloons.
of course that also brings up the pressure differentials from regular thermal conditions too, with air (in the flashlight) contracting and expanding from heat and cool, and makes you wonder what happens if a cargo hold becomes decompressed (a very rare event)???

AW cells are not an exception, they are the Rule, all "certified" (or whatever) li-ion cylindrical cells have a way to releace high pressure and are required to have a pressure anode disconnect, only the cheapest china junk did not, and now most of the china junk does have a releace and disconnect. even a Li-Poly has a cut area that will releace pressure.