WF-400 did this to my 18650 battery. Is this dangerous?

Relatively new CPF member here, and I tried searching for this but couldn't find any threads on it.

Just received my WF-400 (18650-only edition) from DX, and it is a wonderful light, but it doesn't seem to conform perfectly around the 18650s.



Is this dangerous, or is the blue stuff just some non-essential plastic cover?

[/battery newb]

uhhhhh

It seems to me, the protection circuit was pressed against the cell - i would not trust the circuit anymore.

Don't take chances
Get another batt or maybe tape that up and continue to use the batt but monitor it very closely.

Now that I think about it, the first time I inserted the batteries, I did it backwards (it was confusing, I swear! There was a spring on the positive side and some retractable thingee on the tail cap, and usually I think spring = negative). Could reversing the polarity do that much damage?

I put in the second battery from the 2-pack, and it didn't seem to get crushed or damaged or anything. So, maybe the first one was a bit longer than it was supposed to be.

I opted for a single layer of duct tape (hey, at least there's no more battery rattle! ); hopefully nothing will happen.

last fall when i was first personally gettin' involved with the use of Li-ion cells, i had a cut, but otherwise intact, sleeve on a silver UF PROTECTED 18650 cell. tilted the light tail/barrel up and placed the cell into the opening and released it. it quickly slid into the light.

there was a short ARC as the light was disappearing, under gravitational control, into the barrel.

the barrel/batt-tube of the light started gettin' warm/hot *VERY* *VERY* *VERY* quickly. almost as fast as the cell and DereeLight (or Huntlight, i forget which now as my "old-timer's" is actin' up) was heatin' up, ran out side and dumped the cell out of the flashlight onto asphalt. it started spewing out some of its white innards - sorta' like a volcanic magma flow slowly emerging from one end of the cell as the plastic sleeving is meltin', shinkin', and curlin' up from the heat of the self-fueled chemical rxn.

could things get any worse?... stay tuned boys and girls...

...it was trash pick-up friday (i live on a little dead-end street with only 7 houses) and the trash had just been picked up. the garbage truck backs into my driveway to turn around to leave the street (no cul-de-sac on the end, so they either back down the street or use my extra wide driveway as a turn-around) and backs over the cell crushing it slightly. then,...

no sooner does the trash truck pull away, a brief lightning flash (*NOT* from the 18650) followed quickly by the first crack of thunder and almost immediately the heavens opened in a torrential downpour. soon the 18650 was laying in maybe a 1/16" to 1/8" deep stream of flowing water with plenty of water hitting the cell and its white innards.

i run back inside and wait for the "fireworks". 45min later after the storm passes, i go back outside.

no fireworks, no flames, nuttin' at all from the damaged cell. the white innards which were previously being "worn", so to speak, on the outside were all washed away. no flames. no nuttin', period!

Li isn't as reactive with water as some other elements (e.g. K and Na). how people get them to vent with flames (not that that was my intention by any means), and all the talk of water causing Li-ion cells to react violently, i don't know. i believe the claims some of the time - i've seen the YouTube videos of laptop 18650's going "nuclear", so to speak, and sufferin' from a "core melt down", so to speak, complete with flames. [Note: BTW, i've personally seen Na and water react with flames in an Organic Chem Lab during my college days when a classmate dumps his Na pellet down the long water trough between the "stations" on both side of the long lab bench and it ends up in the deep sink at the end of the trough - once the water gets through the oxides on the pellet to fresh Na and reacts with it, ~3' high flames nearly got a guy restin' his tokhes on the edge of the deep sink while flirtin' w/a young lady].

so, back to my account of my own Li-ion personal incident...

...after the storm passes, i go back outside to fetch the cell. it's cool to the touch. all the white innards have been apparently washed away. did i repeat this test by inserting the cell into the flashlight again? nope. my mamma didn't raise no fool. enough excitement for my old heart for one day.

however, if any protection circuitry has been damaged, it might be shorted to the case of the cell (i think this, in some fashion, is what happened to my UF 18650 cell).

my naive, semi-uninformed advice to you is either get rid of the cell (you'd be surprised how hot, how fast it can get if it is shorted), or if you are a "bold-one", using some insulating tape, make sure that sleeve's integrity is restored before use. if you are bold enough to try the second, try it outside in a large area where nothing is flammable. given my experience though and not being able to more closely first-hand examine your particular cell, i'd chuck (i.e. dispose of properly per any legal requirements) the cell and get a new one. don't take a chance. i sure won't in the future, but then, gettin' older, i've grown to be a bit of a wimp with no taste for flames, toxic fumes, and burning houses (especially my own home), as well as most other forms of excitement.

Holy crap!

Good thing we rent!

Seriously though, if I feel the light getting hot REALLY REALLY fast, I will drop it like it's hot. Because it would be...

Hey, duct tape is insulating, right...?

ch33sehead said:

Holy crap!

Good thing we rent!

Seriously though, if I feel the light getting hot REALLY REALLY fast, I will drop it like it's hot. Because it would be...

Hey, duct tape is insulating, right...?

Click to expand...

yes, duct tape (i use Nashua 357 aka "racer's tape" aka "200mph tape" aka "helicopter tape") ought to be insulating (unless it's some sort of "aluminized" duct tape).

however, the issue is NOT just insulating the cell from the barrel of the flashlight, but a possibly damaged protection circuit shorting against the outside metal sleeve/case (which is just under the plastic shrink-wrap sleeve on the outside of the cell).

your duct tape would insure a BETTER contact for that failure mode where the protection circuit monitoring the cell's positive terminal voltage is shorted against the negative metal case of the cell. see now why i said "bold one"?!!! as i stated amidst all of my extraneous verbiage of my prev. Post, that was the likely failure mode of my particular 18650 cell (i must have cut the sleeve and prot. ckt. when i cut the packaging that the pair of cells came in - fault all mine no doubt, not the manufacturer, Ultrafire).

Good point, I did not consider the possibility of the exposed part of the battery shorting against the side. Good thing it falls short of the exposed part of the barrel, right behind the "plastic wrap" you were talking about:



I'm not exactly using aerospace grade duct tape, just some good old fashioned Scotch.

half-watt said:

(i must have cut the sleeve and prot. ckt. when i cut the packaging that the pair of cells came in - fault all mine no doubt, not the manufacturer, Ultrafire).

Click to expand...

I must admit that is a possibility in my case as well. However, I do remember taking extra care when cutting open the packaging, and the pattern of the crack doesn't seem to agree.

i just want to be clear here.

it is NOT just the cell's own prot. ckt. shorting against the battery tube/body of the light that might be an issue. there is also the danger of the cell's own prot. ckt. which monitors the cell's POSITIVE terminal's voltage, shorting against the cell's NEGATIVE casing. this is what happened in my case. if your light cut into or tore through the cell's outer wrapping, then it may(???) have also damaged the delicate prot. ckt too. don't know without a close visual examination.

so, unless you peeled back more plastic sleeving from off of the cell and visually (and electrically) examining inspecting the cell's own prot. ckt. for damage and possible shorting to the cell's casing underneath the cell's own prot ckt, adding insulation to the outside of the cell might(???) be meaningless in your particular cell's case.

please proceed with due caution, bold one!!!


if i may, two unrequested words of wisdom which i oft tell young engineers at work:

1) "Good judgement comes from experience. Experience comes from making mistakes!!"

this can, at times, be somewhat ameliorated by...

2) "Learn from the mistakes of others. You can't possibly make them all yourself!!!"
[Note: though many of us try to make them all ourselves, don't we!!!]

Hello Ch33sehead,

Welcome to CPF.

It appears that the protection circuit has moved. This may involve a connection problem, or it is possible that it may short out.

In any case, it is best to recycle the cell and replace it.

I will move this thread over to the batteries and electronics section of the forum and we can continue on there.

Tom

Hello Half-watt,

Your damaged Li-Ion experience is normal. You are aware that there is not supposed to be an lithium in a Li-Ion cell, aren't you?

If you want to get a reaction with a Li-Ion cell, you need to expose the electrolyte to salt water.

To get the reaction with water, you need to use a lithium primary cell.

Tom

SilverFox said:

You are aware that there is not supposed to be an lithium in a Li-Ion cell, aren't you?

Click to expand...

i am now! now more seriously,...

guess you meant pure elemental Li. if that's what you meant, then 'yes' i was aware.

however, i've seen the chemical formulation of Li-ion batteries and there definitely is Li in there as part of a compound (e.g. LiCoO2 and LiMnO2 as two of the three or four examples i've seen), the Li-ions (nLi+ as i recall, where 'n' is a NUMBER of Lithium ions), as you already know, are transported from cathode to the anode.

so, if you meant pure elemental Li, then you're correct, there isn't really any. howver, if you meant Li in a compound form, then i believe that you are incorrect. people are fond of saying there is no Chlorine in table salt (NaCl) or in a common water purification means (both municipal and backpacking), viz. ClO2, but in both cases they're wrong, unless they mean pure elemental Cl. same applies to your statement, i believe.

please correct me if you feel that i am wrong or have misunderstood you (always a possibility as i'm NOT the sharpest tool in the shed and am a wee bit slow on the uptake). many thanks. i really do learn a great deal from you - if only i could remember it all (thanks for that link in the other Post).

SilverFox said:

If you want to get a reaction with a Li-Ion cell, you need to expose the electrolyte to salt water.

Click to expand...

This raises a question I've been worried about lately: I do a lot of recreating in and around sea water. If a light containing LiCo rechargeables floods, how ugly is that going to be? If the answer is "pretty ugly" or above, that's really going to reduce my enthusiasm for all those AW cells I just ordered. :mecry:

edit: this is getting off-topic, so I'm going to start a new thread.

SilverFox said:

...

If you want to get a reaction with a Li-Ion cell, you need to expose the electrolyte to salt water.

To get the reaction with water, you need to use a lithium primary cell.

Tom

Click to expand...

Any idea which component of Li-Ion electrolyte reacts with salt water? Typically, Li-Ion electrolyte is composed of is a lithium salt and an organic solvent, neither of which are particularly reactive with salt water.

Hi

I have had that kind of damage to the plastic shrink wrap before due to protected cell being longer than std 65mm and getting over compressed ! One cell that it happened to died - damaged circuit board the other lived and now has a little jacket of PVC tape at the end !

To avoid this with protected cells I remove the black piece and its brass insert from the tailcap and underneath is a little spring that works fine and creates a little more room.

Good Luck
Pete

If I am not mistaken, that it the negative end of the cell that has the plastic covering damaged? If so, in general, the protection circuit is on the positive end, not the negative end. I would remove the plastic at that end, see if there is anything there (it may just be a metal end cap) and if nothing\no damage, tape it....but that is me and I like living a touch dangerously. However, pay close attention to the other end and make sure it does not look like it has been compressed/damaged.

Semiman

SemiMan said:

If I am not mistaken, that it the negative end of the cell that has the plastic covering damaged? If so, in general, the protection circuit is on the positive end, not the negative end. I would remove the plastic at that end, see if there is anything there (it may just be a metal end cap) and if nothing\no damage, tape it....but that is me and I like living a touch dangerously. However, pay close attention to the other end and make sure it does not look like it has been compressed/damaged.

Semiman

Click to expand...

Hi

All my protected cells have the protection circuit at the neg end exactly as shown in the photo - you can usually also feel a narrow connector strip, running down the length of the cell, that carries the pos feed to the tail end.

Cheers
Pete

Elemental my dear Half-watt-son,

Sorry for the bad joke...

Lithium metal reacts violently with water. Lithium ions don't. Primary cells have lithium metal in them, secondary cells have lithium ions.

Also, there is no chlorine in NaCl or ClO2. In each case you can break them down, or react something with them to form chlorine, but the products are not chlorine. I will agree with you that they have the potential to form chlorine...

The same applies to Li-Ion cells. It is possible to plate lithium metal onto the electrodes by exposing the lithium ions to very slow charge rate after the cell has been fully charged. This is why the warning to not trickle charge, and why the proper charging algorithm calls for stopping the charge current when it falls to a low level.

The battery manufacturers add additives to try to prevent this, but it is always better to follow the proper charging procedures rather than relying on the additives.

Tom

Hello Buck,

Normal cells, both primary and secondary, will have no problems around salt water. They may corrode a little, but that is about it.

The problems arise when they are damaged and start to leak.

If you can keep from trashing your cells physically while you are out playing, you should have no problems at all.

Tom