Ultrafire 18650 3000mA exploded

[subwoofer]

I don't know where else to post it but I have a question: When a lithium cell explodes inside a flashlight, isn't the aluminum tube / body of the flashlight enough armor to your hand to prevent most dangerous injuries?
Where can I find more information about what happens when a cell explodes inside a flashlight, like does the body explode in splitters or strongly dents?

It is not really the cell exploding that causes the light to explode, it is a build up of pressure from the cell venting gases.

In fact it is the inherent strength of the lights that results in such violent explosions when the happen. The strength allows a massive pressure to build up before catastrophic failure.

Li-ions are really not as unsafe as you might think reading this forum. Think of the number of aircraft crashes and car crashes that are reported and how many journeys are made. The actual number of problems are very small and require quite serious abuse of the cells.

Leaving cells in chargers unattended and overnight can result in serious overcharging and then using those cells in multi cell lights and leaving the light on until the cells are dead and effectively short circuited is asking for trouble.

If you monitor your cells voltage before and after charging and make sure you use similar age/condition cells in a multi cell light and if using unprotected cells, stop using the light when it starts to drop in output, you should be fine.

I have been using cheap fleabay chinese cells, ultrafire cells and top of the range AWs for years and haven't had any trouble. I've discarded cells based on their voltage before charging and their holding voltage after charging. I've even put four unprotected cells in series in an incan and run it until it dimmed. One or two cells felt warm to the touch, and after checking them with a volt meter found they were fine. Li-ions actually perform better when warm, so can take a bit of heat.

[SilverFox]

Hello Anzycpethian,

When "rapid venting" takes place, pressure builds up inside the light. The weakest part of the light lets go and the pressure is relieved.

So far, and this will vary according to the various flashlight designs, the weakest points of lights that have had these rapid venting occurrences have been blowing the head and tail cap off. There are a lot of variables in this and it doesn't happen that often, but IF history predicts future events... this is what you can expect.

Tom

[fcz]

i have recently started to gain interest in flashlights, so i stumbled upon this thread and it worried me a bit (ok, maybe a little more than a bit. ).
then i saw that this isn't isolated case, that these things happen. not often, but still...


this is the flashlight i own:
http://www.dealextreme.com/p/zoom-fo...x-18650-125390
got it with included 18650 battery
http://www.dealextreme.com/p/ultrafi...-26249?item=20
and a charger that plugs directly into the flashlight.

after unpacking, i put the battery into the flashlight, and it worked pretty strong (i don't know how much it was charged). after using it for some days, a friend of mine measured its current at 3.4V. after that, i've charged it with this included charger for an hour, but after charging it was at 3.15V .

then i put it in a friend's charger for two hours, after that it was on 4.16V.

i have a few questions:

1.) what is the lowest/highest safe current value in order to avoid overdischarge/overcharge?
2.) does my charger behaviour sound dangerous?
3.) under what conditions (besides overcharge/overdischarge) can explosion happen? does it happen only when operating and shortly afterwards, or it can happen if the flashlight hasn't been on for some time?
4.) how safe it is for a battery to be in a flaslight all the time? would it be better to take it out if i won't use a flashlight for an extended period of time?
5.) i've red somewhere on this forum that "overdraw" can cause an explosion too. can you please explain me what exactly it is, since i'm pretty much layman when it comes to electronics.
6.) if you have any advice or anything that will help me relieve of this new acquired phobia (), feel free to write it here.

thanks in advance.

[SilverFox]

Hello Fcz,

Welcome to CPF.

First of all current is measure in amps or fractions of an amp called milliamps.

Volts are different.

Full charge on a Li-Ion cell like you have is 4.2 volts plus or minus 0.05 volts.

Full discharge is around 3 volts under load, or 3.4 volts resting.

Next, please understand that these cells don't explode... The can "rapidly vent sometimes with flame" but an explosion is more dangerous. I say this a little "tongue in cheek," but there is a difference.

Rapid venting occurs during over charge, reverse charge, and as a result of using a damaged cell. Also driving a cell beyond its capabilities in either charge or discharge current can heat thing up to a point where the cell will rapidly vent.

Some lights have a parasitic drain on the battery. It is not a good idea to leave a battery in those lights because it can lead to over discharge. With other lights it is OK. Over discharge drops the voltage to below the 3 or 3.4 volts mentioned above.

Your phobia is OK. It is important to pay attention to what is going on when you use and charge these cells. The key is making sure that you are aware and that the phobia is not crippling. I would go so far as to say that a healthy respect is not a phobia but good common sense.

Tom

[Helmut.G]

hi fcz,

these ultrafire batteries are really bad quality, however with a light that only uses one battery at a time you are still relatively safe.
The big majority of incidents occur when multiple unprotected cells are used in one flashlight at the same time (3 batteries in the case this thread is about), or while cells are in the charger (when abused and damaged before).
So never charge cells unattendedly or in a place that will catch fire easily.

your charger's behaviour does sound very strange, even a very cheap charger should not empty a cell under any circumstances.

[fcz]

thanks for your replies.

i still have a few questions.

Some lights have a parasitic drain on the battery. It is not a good idea to leave a battery in those lights because it can lead to over discharge. With other lights it is OK. Over discharge drops the voltage to below the 3 or 3.4 volts mentioned above.

how long is it safe for battery to stay in flashlight? i understand that there are many factors here, but can you say approximately, is it a few days, few weeks...?

where would it best to store the battery out of the flashlight?

so basically, besides attended charging, my only concern should be to keep the voltage between 3.4 and 4.2? if i have any doubts, the voltage measurement should be good enough indicator that everything is ok?

this may be a dumb one, but can anything go wrong when you measure voltage with multimeter?

and could you tell me which 18650 brands are most reliable?

[Shadowww]

and could you tell me which 18650 brands are most reliable?

Panasonic, Sanyo, LG, Samsung, Sony.

[Monocrom]

. . . and could you tell me which 18650 brands are most reliable?

Most reliable would still be AW brand. He's one of us, and cares about reliability along with safety. Check out Lighthound.com as a great site to order them from.

As for your other questions above:

- If you're using a light on a regular bais, it's safe to leave the battery in the light.

- A cool, dry place is a good idea for storage. I'd recommend getting a hard-shell Pelican case for that. These come in many different sizes from the very small to the incredibly large. A worthwhile investment.

- Know exactly how to use a multimeter. These types of cells are no joke. They should not even be handled by anyone who isn't completely familiar with them, the proper way to use them, and the proper way to charge them. There is a very good reason why 18650s and similar cells are not sold to the general public in brick & mortar shops that are open to the public.

[Badbeams3]

What would happen if one of the batteries where put in the wrong way...and then the light turned on?

[STR]

~

I wish Paul had tested those charged cells with a volt meter to see if they got overcharged ?

Why do folks put UN-protected cells in a MULTI-cell light ?

Will they not work with protected cells ? Does it require IMR cells due to current requirements ?

I don't own any multi-cell lights for this reason !

I'm not a Gamblin man .



All > Solarforce L1200 lights should be examined for possible SHORTING HAZARDS
~

I think a better question is why do they sell unprotected batteries at all!? If they are that dangerous no exceptions should even be considered.

[bemymonkey]

Because with a flashlight that cuts off reliably at 2.8V or so (per cell), a decent charger and proper care/handling (including checking your batteries with a voltmeter before and after charge or discharge), protection PCBs are pretty much redundant and can even introduce additional problems... I've even bought an 18650 that's labeled as protected, but doesn't include any circuitry at all - it's just a wrapper over the unprotected cell. Much more dangerous than knowingly using an unprotected battery.

That said, redundancy isn't a bad thing... I've only been using protected cells so far.

[ashcons]

Well...as a budding flashlight enthusiast, I am certainly glad that I stumbled upon Paul's warning story. He convinced me to go with some of the higher quality, protected cells, a higher quality charger (both of which answered questions I had about *fire at Dealextreme and similar sites), and you all convinced me to start with a single cell 18650! Hope Paul recovered from his injury OK!

[yvonne_chan]

Terribly sorry about that!
Hope Paul recovers better now...

[lightliker]

This kind of hazard is the sole reason I bought a Icharger 106B+ for balance charging my 4 Eden 3400 mAh Li-Ion batteries (original Panasonic).
The Ultra fires (they fire 2? ) will be used in my one-battery flashlight (P7).

[B42]

I use Ultrafire 18650 3.7v 3000mAh all the times (in case it's rechargeable cr123a 3.0v-3.6v, i will go for GL brand which is very good). After each charge I will check if the voltage is within limit before putting them back into my flashlight, or stock as spares. I don't use different type or brand of bats in the same light (change all bats at the same time, not half of it). Always the same brand/model/voltage class/mAh. And lastly, I used auto cut-off in my charger (which is Ultrafire WF-139). But becareful, UF is a famous brand and always come out with copies, yes by their own chinese people. There are hi-end chinese lights and batteries companies, but you have to pick the right ones. Never had a problem with genuine chinese brands batteries in all of my night patrols

I recently was a flashlight Li-ion newbie, purchased 6 different sets of "Ultrafire 3000 mAh", started with two sets, they had problems... I bought more from different sellers, returned the others....all sets had different mAh capacities, and several had slightly different shades of red and battery lengths. I did some research and returned all of them I could, bought some Orbtronics, and found that the "Ultrafire 3000mAh" were more in the range of 1400mAh vs my 3400mAh protected Orbtronics run time for comparison. Also, from research, the "famous" company is Surefire, which Chinese Ultrafire/Truefire/Tangisfire/Superfire/Marsfire/Whatever-fire all copy to get people like you and me to think they are the famous standard! I'm glad you had no problems, and check your batteries, but I just wanted to correct some misconceptions about the very over-rated, under quality, Chinese junk batteries being good or a 'standard'! I have also heard reports of false protection on these....hum....I'm staying away.

What I'd like to know is: with my protected 3400mAh Orbtronic cells (I dont use the crappo batteries in anything but my single cell "1600 lumen" light), I see these exploding as unlikely, but is there a way to reduce the amount of explosion power (does leaving the tail on lightly really do this -and create a nice big bullet).

I'm also concerned because after enjoying my 3 cell cheapo lying "3800 lumen" 3x Cree XML T6, I bought a 7x, and since the 26650 Trustfires had been tested on HKJ's site I thought they may be Ok...but am I just leaving myself open to a big bomb if I strike it on a rock hiking with Trustfire use? Nobody seems to know Trustfire 26650 chemistry or reliability, does anyone have info?

[ShawnHu]

If it ok to use unprotected cells in single 18650 lights? Does it matter for single?

[välineurheilija]

If it ok to use unprotected cells in single 18650 lights? Does it matter for single?

If you dont run it too empty and then try to recharge it.possible

[VidPro]

If it ok to use unprotected cells in single 18650 lights? Does it matter for single?

First I gotta say Never Ever, because on many of these blowouts, it was a SHORT, that was the problem, not nessisarily a damaged cell item. So here in the "lets not explode forum" no how no way. The protection protects against dead shorts also.

With that in mind, what lights are people "getting away with" running an unprotected.

Not boost:
It depends on the driver, if the battery can be damaged when used. Some lights using a 18650 might still use a "boost" driver, that can drain a battery down below 0.8v way further down than what would damage a li-ion. So it it still a NO for unprotected in Boost driver lights. With Boost type lights you cannot even see that the voltage has gone way to low.

Not Incandescent:
No for Incadescent lights, because they can drain a battery down to 0, even without showing much light. so thats out.

Lights that stop or slow using single li-ion:
Lights that have a "buck" type driver, or can accept higher voltages like 2x123 usually slow down, lights using the regulator driver usually slow down. both of those when they "fall out of regulation" will only drain to the lowest led voltage it can operate at. These type of lights are the ones people are running unprotected singles in.
These lights usually will not drain the battery down all the way, except given a whole lot of time on.

Direct drive lights, with no driver, will take forver to discharge a li-ion low enough to damage the cell.
Lights that have built in a cut-out to protect the li-ion, can also stop operating before the battery is discharged to far.

In-Conclusive:
So there are light types out there, and you can usually test for the type they are, because they will not operate below the spec voltage. These lights will not easily Damage a li-ion cell from too low of a discharge. But again, you still have no shorts protection.

Side notes:
While there is a PTC for shorts protection built into the cell item, I (myself) concider that it solutions nothing inside a light case. It reduces the current flow during a short, by resistance, it does not stop completly (go open). This resistance is on the top of the cell, the heat comming off the resitance it still contained. So while it will slow things down drasticly, and could prevent a problem, i wouldnt count on it.

[lightcycle1]

This is damn scary, especially to a newcomer like me. I'm considering my first 18650 light, but a single cell only. After reading this, I wouldn't even consider a multiple high power cell light.

The "pipe bomb" comment was interesting. You would think the manufacturers of these lights would incorporate a small, thin machined area of the cell cavity wall, or a threshold pressure plug type of system to allow a minimum force-blowout in the event of a catastrophic battery failure and serious pressure increase.
Would make sense to me to do something like that.

[Helmut.G]

This is damn scary, especially to a newcomer like me. I'm considering my first 18650 light, but a single cell only. After reading this, I wouldn't even consider a multiple high power cell light.

You gotta remember that the guy in this incident used 3 really crappy unprotected batteries (that said "protected" on them but weren't, which he couldn't tell) and didn't own a meter so never checked on their actual charge status.
It's likely that the crappy charger that was used overcharged them, that particular model is known to do that.
I also consider it likely that Paul unknowingly overdischarged them from time to time.

The light was a very high-powered incandescent one, that would've pushed the limits of most good batteries available then.
The batteries used were possibly never in balance to begin with - "recycled" dead cells extracted from laptop batteries are known to be sold with that particular "brand" wrapper on them.


Paul knew none of this and nearly lost his thumb. But you do know - so don't misuse crappy batteries that belong in the junk and don't be afraid.
Of course, a risk remains. But that goes for living in general.

The "pipe bomb" comment was interesting. You would think the manufacturers of these lights would incorporate a small, thin machined area of the cell cavity wall, or a threshold pressure plug type of system to allow a minimum force-blowout in the event of a catastrophic battery failure and serious pressure increase.
Would make sense to me to do something like that.

When most buyers don't care/know about the possibilities/issues the manufacturer doesn't improve the product - even if a massive improvement would be easy and cheap. That's the way it has been for decades. It's called capitalism.

[Felco]

I may also take off any waterproofing gaskets and O-rings as well, I hardly ever go out in the rain at night.

I only use NiMh batteries nowadays (eneloop only). I won't even use alkaline batteries because one nearly blew the cap off a flashlight by outgassing hydrogen.

Tip: drill a tiny hole for venting in your flashlight if you use anything other than what I use (unless, of course, water penetration worries you).

[RCM]

NiMH can vent hydrogen when over-discharged as well...Alkaline cells usually leak when they vent as well..