Surefire explosion

[Size15's]

here's the odd thing about my "M3T" [M3 body, M6 head]
Fresh surefire 07-2017 batteries [all 100%] goes in, MN15 runs for 30 minutes....then head cell goes 60-80%, second cell 80%, tail cell 100%. Run it until it dims, and test all the cells. head cell 40%, second cell zip, tail cell 80% via ZTS.

It's just bizarre to me, I'm using 0509A energizers now...and so far its 80-80-100 and through a KL6 head, the MN15s back on the M6:nana:

I'm sure that'll be heat. Batteries work better as they heat up. The ones closer to the bezel will heat up faster.
We know that CR123A batteries are strong and robust and tolerant.
Being responsible with batteries means not disadvantaging them right from the start.
If the behaviour you noticed using the ZTS was usually and normal use was a problem we'd all be in a world of hurt. Since we're not I think that responsible normal battery practices coupled with responsible flashlight practices are sufficient to minimise battery-related incidents to the extent they are a non-issue.
Mix batteries and act carelessly not disabling your flashlight and you dramatically increase the risks. Even so the chances of being bitten by your sloppy and irresponsibly behaviour is low. Which isn't the constructive reinforcement of positive behaviour that will make the world a safer place.

Al

 

[matrixshaman]

In following Lux's sharp detective work I rotated that pic and used a sharpening filter on it to notice this interesting bit. This is speculation and could of course just be coincidence but it does look a bit like a Battery Station logo left imprinted on the burnt battery:

Battery station next to a Surefire and you can see the letter 'B' in it appears identical and in roughly the same location from the end of the battery as the burnt one. I will say however it appears on the wrong end based on the lip (but BS did change manufacturers a while back so the labels may have been put on differently). BTW this is not a slam on Battery Station batteries as I know Kevin changed manufacurers for his cells a while back and has done a lot to keep them safe. It's just that after looking close at the picture above it looked like it might be a Battery Station battery but no way to know for sure from the pic.

 

[McGizmo]

I seem to recall one event that was reported in a two cell light where it was reported to have gone dim, turned off and then the event occurred many minutes later? Point or question being can the event be triggered and then even breaking the circuit not be enough to stop it from "running away"?

I could be wrong here or have a bad recall.

One consideration I have come to on my own and in bench testing new designs as well as trouble shooting lights is the policy that if a light does not appear to function properly, it is not a good host for battery(s) whether it appears to be turned off or not. With a clickey switch, you can't be certain anyway, if the light isn't lighting up.

With multi cell lights would it be a good habit to immediately empty a light that is not performing to par on its current battery set?

Here's another conjecture in regards to a twisty type ground path. As you twist the light off, I assume it is conceivable that you have a certain range in which you have yet to completely break the circuit but there is sufficient contact resistance to keep the light from appearing on; especially in the case of an incandescent? You also have the back lash in the threads which allow for some Z axis play. I know I and others have experienced with a sealed light cases where changes in relative temperature and pressure have activated a light that was off. Twisting until the light just turns off may not insure that the light will remain off. Further twisting is really a good idea.

If the event reported here required a complete circuit to occur then it might be a good idea to figure out how that complete circuit came about. Al's comment about a lock out tail cap is significant I think and adding the potential of internal VS external pressures' influence on the state of the ground circuit may have been a key contribution.

Obviously given the number of multi cell lights out there and the atypical nature of this event, as users of these lights, we would love to have a handle on what the nature of this event was. My gut tells me that if this light was host to SF batteries that it was a case of depleted cells with disparity in individual charge levels and likely a closed circuit.

 

[xpawel18x]

I just found this article on Surefire's website and it says:

"SureFire has been manufacturing lithium battery-powered flashlights for nearly 25 years; in that time not a single incident has been reported of a SureFire 123A lithium battery causing any such mishap in a SureFire brand flashlight."​

Could this be the first SF battery incident reported?​

http://www.surefire.com/surefire/content/graphics/pagebuilder/pdfs/Battery-Explosion-Warning.pdf​

 

[Size15's]

I suspect that SureFire would want to examine the flashlight and what is left of the batteries before reaching a conclusion.

 

[Burgess]

If only there was a way to tell whether a battery was unused or used.
It's not about determining how used it is: Only whether it has been used at all [because the 'rule' is only put new unused batteries in flashlights]

Perhaps an adhesive tab on one of the terminals that the user peels off. It would leave no residue and wouldn't be sticky enough to be stuck back down.
I'm sure 3M could make something like that.

Ray-O-Vac had this very feature on their "C" and "D" cell batteries, in the early 1960's.

They called it the "Safety-Strip"

Or perhaps it was "Safe-T-Strip"


Even as a boy of maybe 10 years of age, i thought it was a pretty good idea.


Ray-O-Vac eventually dropped it, however.

 

[LuxLuthor]

I'm sure that'll be heat. Batteries work better as they heat up. The ones closer to the bezel will heat up faster.
We know that CR123A batteries are strong and robust and tolerant.
Being responsible with batteries means not disadvantaging them right from the start.
If the behaviour you noticed using the ZTS was usually and normal use was a problem we'd all be in a world of hurt. Since we're not I think that responsible normal battery practices coupled with responsible flashlight practices are sufficient to minimise battery-related incidents to the extent they are a non-issue.
Mix batteries and act carelessly not disabling your flashlight and you dramatically increase the risks. Even so the chances of being bitten by your sloppy and irresponsibly behaviour is low. Which isn't the constructive reinforcement of positive behaviour that will make the world a safer place.

Al

Al, I want to play devil's advocate for a minute. I just looked at my L2, M4, M6 boxes and enclosed papers. I keep everything. There is absolutely nothing in these about using fresh batteries, not mixing with used, locking out the tailcap, or removing batteries when not using. Nor is there anything specific about the dangers of the 123A cell.

There is some minor battery instructions in the most recent SF E2D I got, but not what I would consider adequate warnings.

I do not think you can expect the average consumer to know the dangers on primary Lithium cells unless they are clearly warned and don't read/follow those enclosed instructions. You certainly cannot say they are being irresponsible. Well I take that back. You can say it, but it is not accurate.

In fact, if any fire, damage, bodily injury, or loss of life occurred from older SF lights & batteries, I guarantee that a lawyer would eat SF alive. Regarding product safety litigation, the company would be held irresponsible and liable if they did not give adequate warnings to the consumer for dangers they know about, and which in my lights SF did not.

In addition, several boxes I bought this year with expiration dates of 5/2018 also say absolutely nothing about safe use of the cells. There are warnings on observing proper storing, but nothing about safe use, not mixing old with new. I guarantee that guidelines which we know as members of this forum is not common knowledge.

I brought my poor understanding of Alkaline, NiMH, NiCad batteries to Lithium primary and secondary cells when I first joined this forum. I would always just replace the weak battery when tested on one of those cheap hand held battery testers, and had no reason to think it was any different with Lithium batteries.

In this specific (and other) example on AR15 forums, it is not the responsibility of the consumer to later somehow find out that his light should be only used with a lockout tailcap, and follow specific battery use guidelines. Rather, the responsibility rests with Surefire to issue notices to consumers they know bought certain lights, distributors, retailers, and place product safety announcements in public magazines/newspapers to protect the public.

 

[Size15's]

Are you sure?

All the SF12BB boxes have warnings about storage and use. That's the old white packaging as well as the current.

I've had SureFires with specific leaflets in the packaging on batteries.

WARNING Where there's light, there's heat. WARNING
An important word of warning...please read
[a whole load of safety warnings and recommendations]

It's so ubiquitous but I'm sure this leaflet in some form as been supplied in every CR123A powered SureFire package I've got.

And I'm sure it's in the manuals...

One of my M6 manuals (Rev. 6 4-1-2000, the first one to hand) states

Note: Use only Duracell DL123A batteries in order to achieve the high output expected from the M6 flashlight. Replace batteries as a set of 6.

And

CAUTION
The SureFire M6 Flashlight is very powerful.... The Flashlight has a Lock out Tail Cap, one revolution of the Tail Cap locks out the switch. Make sure the lamp is OFF before storage to prevent overheating damage to the Flashlight or nearby objects...

And

WARNING
Lithium batteries can explode or cause burns if disassembled, shorted, recharged or exposed to fire or high temperatures.
Please handle with care.

I've not got the most recent packaging to hand (LX2, A2L etc). I'm sure I saw similar leaflets and warnings in the manuals of those...

Al

 

[Vesper]

I'm beginning to sound like a broken record in that thread. Where's that dead horse?

Use the LockOut TailCap.
If your flashlight doesn't have one then get one, or replace the flashlight with one that can be disabled.

Not sure, how would this protect someone during normal flashlight use? Lockout mainly is best for storage and transportation. It would be impractical to keep engaging / disengaging this. The guy had it ready to go on his duty belt when it occurred.

 

[Size15's]

Not sure, how would this protect someone during normal flashlight use? Lockout mainly is best for storage and transportation. It would be impractical to keep engaging / disengaging this. The guy had it ready to go on his duty belt when it occurred.

I have acknowledged that there are situations that require the flashlight be ready for use such that using the LockOut feature is not practical.
Carrying a flashlight for instant use in a Speed Holster is one of the best ways of doing so.

The LockOut TailCap design with it's fixed limited travel switch contact assembly is far less likely to be in a position where it could be in intermittent partial contact as in the scenario that Don describes above. For example it is very difficult (impossible?) for a LOTC switch contact assembly to be out of alignment unless it has become jammed against a thread. In which case the switch is obviously jammed and the user would realise something is wrong.
The free-floating unrestrained nature of the switch contact assembly in a non-LOTC means there is far more potential for off-nominal switch contact scenarios and for this to occur unnoticed by the user.

I don't believe I'm clutching at straws here [am I?]

 

[Illum]

Not sure, how would this protect someone during normal flashlight use? Lockout mainly is best for storage and transportation. It would be impractical to keep engaging / disengaging this. The guy had it ready to go on his duty belt when it occurred.

Other than the need for more lube frequency theres not much that can go bad to keep engaging / disengaging your lights, just have to remind yourself that the light is locked out before you approach the scenario that requires your flashlight.

I lock/unlock my flashlights all the time, but something still bothers me with this incident, particular on the batteries. Surefire has been using the newer, red boxes for orders of 12 or so...but something keeps telling me the older boxes are still being used, for bulk orders of say 100 or more. I cannot, however, find credible evidence for this assumption. :thinking:

 

[Size15's]

The SF72BB 'bricks' (six boxes of 12 (SF12BB), in a box) I've used for the last couple of years have been the current style.

 

[MorePower]

I'm sure that'll be heat. Batteries work better as they heat up. The ones closer to the bezel will heat up faster.
We know that CR123A batteries are strong and robust and tolerant.
Being responsible with batteries means not disadvantaging them right from the start.

Al

The thing is that the same number of electrons will flow through all 3 cells because they are in series. Ie. you can't discharge the cell in the head of the light more deeply than either of the other cells.

Also, you stated earlier in this thread, "The flashlight would not have acted this way unless it was activated, even only slightly, especially in a confined space like a pouch or clothing where the heat building up could not escape. This can't happen in disabled flashlights, even when the batteries are damp and whole mix of discharge states as the electrical circuit is not complete and the compromised batteries are not being stressed."

Locking a light out will prevent overdischarge and cells going into reversal, but lithium manganese cells (CR type) can vent / explode / etc even if they are not subjected to conditions of overdischarge or overheating. It is rare, but internal shorts can form in partially discharged cells, thermal run away can occur, and a fire or explosion can result.

Locking a light out is a good habit to get into, but it can not prevent these types of occurrences 100% of the time. It will, however, greatly reduce the possibility.

 

[McGizmo]

The thing is that the same number of electrons will flow through all 3 cells because they are in series. Ie. you can't discharge the cell in the head of the light more deeply than either of the other cells.

....

From both some bench testing as well as based on my understanding of how these cells work and given their relationship to efficiency as based on operating temperature, I completely disagree with the quoted statement above with the exception of the example which is too confusing for a simple response. The battery close to the head would likely discharge less than the one at the tail because it likely is operating in a more efficient temperature, in most cases. The battery's ability to contribute electrons to the stream is temperature dependent and the fact that the battery depletes is because it does contribute electrons?!?! Am I missing some logic here?

 

[Size15's]

The thing is that the same number of electrons will flow through all 3 cells because they are in series. Ie. you can't discharge the cell in the head of the light more deeply than either of the other cells.

I agree with Don; this can't be so.
Your explanation for why some batteries are fuller than others is because some where fuller to begin with? How does this explain that the battery at the bezel end has been shown to be the one that discharges the most (I've found this to be so myself with plenty of sets of batteries through the 12PM)

Locking a light out will prevent overdischarge and cells going into reversal, but lithium manganese cells (CR type) can vent / explode / etc even if they are not subjected to conditions of overdischarge or overheating. It is rare, but internal shorts can form in partially discharged cells, thermal run away can occur, and a fire or explosion can result.

Rare seems too strong a term for such an occurrence? I'm not aware of any instance of a lone used CR123A battery being observed to go into thermal runaway, catch fire or 'explode'.
I've not aware of any instance of a battery going bad in a single-cell flashlight where accidental activation can be ruled out beyond all reasonable doubt.

 

[MorePower]

From both some bench testing as well as based on my understanding of how these cells work and given their relationship to efficiency as based on operating temperature, I completely disagree with the quoted statement above with the exception of the example which is too confusing for a simple response. The battery close to the head would likely discharge less than the one at the tail because it likely is operating in a more efficient temperature, in most cases. The battery's ability to contribute electrons to the stream is temperature dependent and the fact that the battery depletes is because it does contribute electrons?!?! Am I missing some logic here?

Let's see if I can clear up any issues with my statement.

1. Electrons flow from the lithium metal anode, through the filament, and back to the manganese dioxide cathode of the cell. This is what is called a redox reaction (reduction-oxidation).

2. 2 or more cells in series will each have the same number of electrons flow through them. I think we can agree that they are, in this sense, acting like a piece of wire used to complete a circuit.

3. Efficiency of discharge is improved at higher than ambient temperatures, but since the same number of electrons flow through each cell in series, you can't get into an imbalanced situation with regard to depth of discharge unless the cells contained more or less lithium to start with (CR cells are anode-limited, which means that there is an excess of cathode material).

If this is still unclear, I'll check back into this thread later and try to expand upon this explanation.

 

[MorePower]

I agree with Don; this can't be so.
Your explanation for why some batteries are fuller than others is because some where fuller to begin with? How does this explain that the battery at the bezel end has been shown to be the one that discharges the most (I've found this to be so myself with plenty of sets of batteries through the 12PM)

How did you test the cells? ZTS? I have doubts as to the validity of ZTS results on partially discharged CR-type cells. The only way to know for sure is to use a setup that can count coulombs and to completely discharge the cells to zero volts. CR123A cells are made to tight tolerances, but there can be variation in lithium content from cell to cell.

Rare seems too strong a term for such an occurrence? I'm not aware of any instance of a lone used CR123A battery being observed to go into thermal runaway, catch fire or 'explode'.
I've not aware of any instance of a battery going bad in a single-cell flashlight where accidental activation can be ruled out beyond all reasonable doubt.

Personally, I am aware of single, partially discharged cells catching fire spontaneously.

 

[Size15's]

I think you're going to have to because I'm not understanding your explanation and doesn't seem to fit with what is being experienced.

Are you're saying that a partially used battery in series with a full battery acts to limit the amount of stored energy the full battery can release [and that once the partially used battery is drained it is impossible for the other battery that still has charge in it to provide this to the circuit.
Also, that it doesn't matter which order these batteries are in - they will only ever discharge the amount of energy that the least-full battery has.

The least-full battery in a series of four (in the M4 for example) could be anywhere. Heat has no influence other than to make it easier for the battery closest to the bezel to discharge but it won't discharge any more than the less-full battery. Heat influences the rate of discharge only and not the amount?

With regards to 'reverse charging' - are you saying that the CR123A battery can not discharge any charge gained through 'reverse charging'?

 

[MorePower]

Are you're saying that a partially used battery in series with a full battery acts to limit the amount of stored energy the full battery can release [and that once the partially used battery is drained it is impossible for the other battery that still has charge in it to provide this to the circuit.

No, I'm saying that unless the cells have an unequal amount of stored electrochemical activity to start with, you can't get imbalanced cells at the end of discharge. In the case of CR123A cells, the amount of lithium metal in the cell is the limiting factor for capacity. A lower capacity cell can undergo reversal if put in series with a higher capacity cell, but only if there is sufficient voltage across it to drive the reactions which occur in that case.

Also, that it doesn't matter which order these batteries are in - they will only ever discharge the amount of energy that the least-full battery has.
The least-full battery in a series of four (in the M4 for example) could be anywhere. Heat has no influence other than to make it easier for the battery closest to the bezel to discharge but it won't discharge any more than the less-full battery. Heat influences the rate of discharge only and not the amount?

Heat influences the efficiency with which a cell can discharge. Warmer cells can reach greater depths of discharge while maintaining higher CCV. Likewise, a warm cell undergoing discharge can hold the same CCV as a cold cell under a lesser discharge rate.

However, because the cells (in an M4, to take your example) are in series, the same number of electrons flows through each of them, so final depth of discharge is entirely dependent on initial metallic lithium content.

With regards to 'reverse charging' - are you saying that the CR123A battery can not discharge any charge gained through 'reverse charging'?

When you refer to reverse charging, can I take it to mean that you're speaking of cell reversal? That is, when cells of unequal capacity are discharged in series with each other, the lower capacity cell can exhibit a condition where the cell voltage reverses? No charge is gained during cell reversal, so there is no additional charge for a reversed cell to discharge.

Really, I don't mean to be confrontational or pedantic about this topic. If you'd like to continue this via PM I'd be more than happy to do so, and avoid further cluttering this thread.

 

[Size15's]

Thanks for taking the time to explain - I'm learning new things about batteries.