A Little Accident. W/123's and a Peli. M6

[Ray_of_Light]

Re: A Little Accident. Enjoy.

Cheap, safe and good: pick any of the two.

1. Buy cells of known quality.

2. Since it can be a bogus cell among quality ones, before sealing indefinetively 123s in a multiple cell flashlight, flash-amp the cells.

3. Inspect the cells after a violent drop of the light. That's the moment when most of the cell leak/explosion takes place.

4. Do not mix different brands in a multiple cell flashlight, and replace all the cells at once.

5. Be afraid to seal inside a flashlight cells that are close to end-of-life, or are defective in any manner. Unforeseen, and often nasty things happens mostly with discharged/bad cells. Throw away cells that you now are depleted more than 90%.

6. Single cells lights are safer. Low drain lights are safer.

7. An explosion can happen, by mean of various dynamics, with all type of cells, not strictly with lithium 123s. Statistically, the alkalines are the most prone to catastrophic failure, but there are very few sealed lights using alkalines. Also, they are less energy-dense than lithium.

8. The explosion of a cell is a very rare occurance. Good to be aware of, but unlikely for you to experience it.

Anthony

EDIT: The lithium 123 leaks some nasty chemicals, when mechanically abused or attempted to recharge. These chemicals will corrode both plastic and metals.

In the case presented here, the explosion very likely has dispersed all reactive chemicals. THe residue you see is mostly composed of degraded manganese dioxide, which is not toxic by itself.
Lithium dust, which may be contained within, may pose an healt risk if inhaled or ingested, since is very reactive (as proven).
Better to vacuum clean the all room.

 

[beezaur]

Re: A Little Accident. Enjoy.

Lurker writes, "What should I be doing to avoid this?"

If I understand correctly, you can measure the current with one probe on each terminal of the battery (quickly). This checks the health of the battery, or at least a major aspect of it. A bad one won't do 6-7 A. Toss any that fail this test, and only put fresh batts in the light.

No cheap or untested batteries. Partially used batts go in a single-cell light, or at the very least get matched for current if put into something like an Inova X5.

That's my plan.

[edit: oops, you just beat me with that /ubbthreads/images/graemlins/wink.gif ]

Scott

 

[Lunal_Tic]

Re: A Little Accident. Enjoy.

[ QUOTE ]
RY3 Said:
Quote:
--------------------------------------------------------------------------------
While a thirst for knowledge may be good, it might be best to let "sleeping dogs lie" in
this case. Pushing too hard for info might cause another type of explosion...
--------------------------------------------------------------------------------
I really wish you gave me this warning earlier.


[/ QUOTE ]

Sorry RY3, been there done that myself. I was thinking it as soon as you mentioned her hesitance but didn't mention it till later. My bad.

-LT

 

[NewBie]

Re: A Little Accident. Enjoy.

RY3,

Kudos on the photos, very nice.

That Pelican M6 sure had alot of crud in it, and to think alot of it spilled out as it rolled across on the floor.

For typical 123 cells:
http://data.energizer.com/PDFs/123.pdf
http://www.duracell.com/oem/Pdf/123.pdf

So, whats really in them?
http://data.energizer.com/PDFs/lithiummangdioxide_psds.pdf
http://www.duracell.com/oem/pdf/msds_2003.4.pdf
http://www.duracell.com/oem/primary/Lithium/composition.asp

 

[Vrt]

Re: A Little Accident. Enjoy.

[ QUOTE ]
Ray_of_Light said:
2. Since it can be a bogus cell among quality ones, before sealing indefinetively 123s in a multiple cell flashlight, flash-amp the cells.


[/ QUOTE ]


[ QUOTE ]
beezaur said:
If I understand correctly, you can measure the current with one probe on each terminal of the battery (quickly). This checks the health of the battery, or at least a major aspect of it. A bad one won't do 6-7 A. Toss any that fail this test, and only put fresh batts in the light.


[/ QUOTE ]

Isn't shorting a cell through amp-meter dangerous ? I've read that CR123A cells shouldn't be shorted . Can't it explode at that moment ? From Duracell's MSDS (http://www.duracell.com/oem/Safety/pdf/2031_4.pdf):

[ QUOTE ]
Handling and Storage
Store at room temperature. Avoid mechanical or electrical abuse. DO NOT short or install incorrectly.
Batteries may explode, pyrolize or vent if disassembled, crushed, recharged or exposed to high temperatures.
Install batteries in accordance with equipment instructions. Replace all batteries in equipment at the same
time. Do not carry batteries loose in pocket or bag.


[/ QUOTE ]

"DO NOT" is capitalized and in bold, so it may be very important.


[ QUOTE ]
beezaur said:
3. Inspect the cells after a violent drop of the light. That's the moment when most of the cell leak/explosion takes place.


[/ QUOTE ]

What does the "violent drop" means ? If EDC light (with CR123A) falls from 1-2 meters on concrete is it violent enough to be dangerous ?


[ QUOTE ]
beezaur said:Unforeseen, and often nasty things happens mostly with discharged/bad cells. Throw away cells that you now are depleted more than 90%.

[/ QUOTE ]

How do I know that the cell is depleted too much ? I want to use a regulated flashligth. When should I worry about security ?


[ QUOTE ]
beezaur said:
7. An explosion can happen, by mean of various dynamics, with all type of cells, not strictly with lithium 123s. Statistically, the alkalines are the most prone to catastrophic failure, but there are very few sealed lights using alkalines.

[/ QUOTE ]

Alkalines are more prone to catastrophic failure that CR123As ? Are they more dangerous than lithiums ? I didn't hear too much about alkaline-powered equimpent explosions.

 

[beezaur]

Re: A Little Accident. Enjoy.

I think some of those quotes are not attributable to me, and where they are, I am mostly getting my information from Ray_of_Light's posts. He knows far more than me on this topic.

From what I do know about chemistry, I would say that it is not dangerous to short the battery for testing for a second or two. I think what they mean is that you should not leave the battery short circuited for any length of time. If I understand correctly, the battery will explode if 1) thermal conditions get bad and 2) the battery's safety features malfunction. I would not depend on (2), but (1) shoiuld not have a chance to develop in 1-2 s. Certainly I have never been able to feel any heat accumulation.

Dynamics of impact is a topic in which I have both experience and training.

The problem with dropping, as they say, isn't the fall, but the stop at the end. You have two materials, the light and the impact surface, that come into contact at the end. The velocity and the elasticity of the two materials are what determines what the acceleration is that generates the destructive force.

If you drop a beanbag on a feather bed, there is a pretty low acceleration (deceleration if you prefer). A beanbag on concrete is more acceleration, and an aluminum block on concrete is more yet.

The feather bed might produce a stop in 1/4 s (time t). At 5 m/s (velocity v for a drop of a little more than 1 m), that's v/t = 20 m/s^2, or about 2 "Gs."

A drop on concrete might stop a beanbag in 1/50 s. That's 250 m/s^2 = 25 Gs.

Metal on something like concrete not only stops the fall, but reverses the velocity entirely. The velocity change is double because of bounce.

I haven't measured time taken to bounce aluminum off concrete, but it is eceedingly small, say 1/250 sec to reverse the velocity from down to up: 2x(v/t) 2500 m/s^2 = 250 Gs. (Our dropped metal object is exposed to 10x the acceleration of the soft object in the same drop to the same surface.)

If you take something that weighs 15 grams and expose it to 250 Gs, it will "weigh" 250x15 = 3750 grams during that time. If you have two of those somethings, they will weigh 7500 grams together -- 7.5 kg (17 lb) is the force produced by both.

Exposing a small seal to that much force all at once will probably deform it.

The true situation is much more complicated because you have a variety of materials that can move in relation to one another, deformations will absorb energy, and some of the energy will undoubtedly go into rotation.

All the math aside, the underlying point is that surprisingly large forces can be developed even in a short drop.

So yes, check your batteries after you drop your light.

Scott

 

[Ray_of_Light]

Re: A Little Accident. Enjoy.

"Flash-Amp" a cell means to measure the instantaneous short circuit current, to have an overall indication of the status of the cell.
Manufacturers, of course, do not endorse such practice; if you search the CPF archives, there are many indications on how properly conduct this test safely.

There is another historical issue about alkalines and sealed lights. Alkalines can release hydrogen when are too drained, or reverse charged. If this happen in a sealed light, and it this happened to me, you get a loud "boom".
On the other hand, an alkaline cell will not "esplode" like a defective 123 could, as we have seen in this thread, due to the different energy density and chemistry.
There are episodes documented here on CPF and I suggest you to conduct an archive search.

Hope this helps

Anthony

 

[cheapo]

Re: A Little Accident. Enjoy.

I have contacted Pelican and had the poster E-mail them. They are going to replace his light. That is great customer satisfaction heh? That just shows that whatever happens to your Pelican light, you can always be assured that Pelican will replace your light if it is broken. That is a reason why I bought my Pelican, and they are top-quality products.

-David

 

[Mags]

Re: A Little Accident. Enjoy.

Is there a bigger chance that Incan 2 cell lights will explode? or 2 cell LED lights?

 

[NewBie]

Re: A Little Accident. Enjoy.

Depends on the current draw, and if the converter for the LEDs inside has a minimum voltage cut-off.

The cut-off feature is a definite *major* benefit for some converters (boost or buck). Some converters just skip this important safety feature, and can suck cells dry, which can lead to the possibility of reverse charging of one cell by the other cell. Other converters just naturally cut-out since they can't run at the lower voltages.

Pretty much any cell chemistry where you start reverse charging is a bad idea.


It's really nice of Pelican to pick up the tab, even if it had SureFire cells in it....

 

[RY3]

Re: A Little Accident. Enjoy.

Just want to confirm that Pelican has contacted me (Thanks for David) and offer to replace my PM6. They also ask if I like to try the LED version instead.

Is Pleican the only one who advertises offers "you break it, we replace it, forever"? I wonder if UKE offers the same?

BTW, I finally took the PM6's head off to check it out. Attached is a picture if anyone interested.

 

[NewBie]

Re: A Little Accident. Enjoy.

The filament supports in the bulb look interesting. Can you get a shot of them such that each support is visible?

 

[deranged_coder]

Re: A Little Accident. Enjoy.

[ QUOTE ]
RY3 said:
Is Pleican the only one who advertises offers "you break it, we replace it, forever"? I wonder if UKE offers the same?


[/ QUOTE ]
Surefire's guarantee is somewhat similar. To quote their website: "Lamps will burn out, batteries will be used up, and tape switches for WeaponLights™ will eventually need to be replaced. Everything else is covered by our lifetime no-hassle guarantee: If it breaks, we fix it!"

My own first-hand experience with Surefire customer service was quite good.

 

[RY3]

Re: A Little Accident. Enjoy.

[ QUOTE ]
NewBie said:
The filament supports in the bulb look interesting. Can you get a shot of them such that each support is visible?

[/ QUOTE ]

Here you go...

The other side..

 

[chevrofreak]

Re: A Little Accident. Enjoy.

I think the huge filament is the reason my Pelican M6 casts such a crappy beam. With a smooth reflector its a very wide oval beam, and you can actually see the loops of the filament in it. /ubbthreads/images/graemlins/frown.gif

 

[captjlw]

Re: A Little Accident. Enjoy.

UK did a great job for me. I sent a light back that had some age on it after the plastic lens broke out sending the batteries into the ocean. Yes I was just about to step overboard for a night dive. They didn't fix it, they sent me a new current edition model. No questions asked. /ubbthreads/images/graemlins/smile.gif

 

[Size15's]

Re: A Little Accident. Enjoy.

Those are great photos!

 

[dano]

Re: A Little Accident. Enjoy.

That's an old M6 lamp! The newest ones are one piece integrated with the reflector.

-dan

 

[SilverFox]

Re: A Little Accident. Enjoy.

Hello all,

I have been spending quite some time checking into this. Everywhere I look, I keep getting pointed in the same direction.

It seems that the most reliable way to get a primary Lithium CR123A cell to heat up and "rapidly vent with flame" is to subject it to a moderately high current.

These cells have a PTC protection device built in. Its function is to create an open circuit in the presence of a dead short, or under high thermal conditions. The PTC circuits are available in different current ranges. It will reset a limited number of times when the temperatures reduce to a safe level.

We all know that cells discharge at different rates in a multi-cell light. Some people rotate the cells thinking that the position "in the stack" makes a difference, others will throw both cells out and replace with fresh cells, and still others will check the voltage and replace the "low" cell with a new one.

When you have a cell potential imbalance and you turn the light on, the full cell tries to charge the low cell and bring things to equilibrium. In the case of a slight difference, not much happens. If you have a new cell put in with a worn cell, heat can be generated and since this is not a "dead short," the PTC trip current may be higher than the actual current while this is going on. Pressure can build up inside the cell and poof...

I am not pointing fingers here. Once again, let me say I am not pointing fingers here, but if someone unfamiliar with lithium 123 lights "borrowed" one, turned it on only to find the output dim, replaced a single cell and used it, we have the stage set for problems.

If any of this is close to what is really going on, an important part of using our lights would be to educate those around us that when the light goes dim, throw BOTH cells out and replace them with new.

I must admit that I have several used cells sitting around at different states of being used up. On occasion, I have grabbed whatever cells were handy to run a series of tests on a multi-cell light. I now have gathered up all my partially used cells and placed them in a zip loc bag that is labeled "Only for Use in Single Cell Lights." I have also instructed my family to not replace only one cell (I actually told them just to grab another light and I will take care of the re-loading /ubbthreads/images/graemlins/smile.gif ).

Tom

 

[JackBlades]

Re: A Little Accident. Enjoy.

Excellent post, Silverfox!
Ever since I joined this board, and susequently began using multi-cell 123 lights, I have checked ALL cells with my DMM before loading. This includes checking/balancing used ones in my X5T. Just seemed like the smart thing to do.

I must admit that when I stumbled across this thread my eyes opened in awe. I had no idea something like this could happen!