Did anyone see this line in a quote?
“Took the light apart when it got here, because that’s what I do. It came off with a lot of effort. When I went to put it back on, it took a wrench. So now the switch is stuck on the light body. Which is ok, unless the switch breaks. ”
There was something wrong from the get go. The tailcap was put back on WITH A WRENCH! Yikes! Could it be that the cells were compressed, nearly frozen and then turned on and got hot under pressure and oops!?
LiPo (pouch cells) and LiCo (18650 cells) are pretty much the same thing… just a different package.
If this was a solarforce host, how did he get the batteries out if the switch was stuck? something definitely sounds off.
……………………
This streamlight scorpion is marketed to and very popular with LEO’s, and I remember seeing it advertised somewhere that the rubber casing is “great for holding in your mouth when you need both hands free.” 2 CR123’s in series in my mouth? no thanks!
I read through the thread over at the other forum last night.
It seems like a legit thing that happened.
It appears he was fairly new to the ‘flashlight scene’, having only recently joined over there, & had a few posts asking for recommendations on inexpensive lights.
Never having spent much time at the other forum, it gave a good insight into the amount of effort the moderators put in 0:)
pilotdog68, the battery can be removed/inserted by removing the head of the SF lights I have.
TP, the light wasn’t out in the cold truck, he had it with him in the house.
Seems like he’s recovering fine.
No...
The only time there is danger with parallel cells is when they are inserted in the holders. If the voltages are different, then there may be a sudden big current rush to equalize the voltages. Perhaps even so big current that the batteries heat up, or wires between them, plastic may even catch fire. This is easily avoided by only inserting all batteries at once, and only if just fully charged to the same voltage. They are then all typically at 4.2 volts. While the batteries are used the voltage will fall, but will be identical for all batteries. There could perhaps be a problem if you mix chemistries, for instance batteries that may be discharged to 2.5 volts with batteries that can be damaged at that voltage.
When used in series the batteries does not have to have the same voltage when inserted. There will be no sudden current rush if batteries with different voltage are insertes. However if the batteries have different capacity, are unbalanced, then there may be danger when one of the batteries are exhausted long before the other(s). The discharged battery will then act as a resistor in the circuit and warm up and the voltage over the battery may fall dangerously low. And permanently destroy the battery or even cause it to vent suddenly (explode).
Parallel: Same voltage when inserted!!! Safer otherwise.
Series: Same capacity!!! Preferable even exactly the same model and the same age. And charged the same.
the appearance of the burned cells in the video looks like he had two CR123 cells or two 16340 cells in series in the light. As mentioned above its possible they were unprotected and/or one was low or dead thus when he turned the switch on the cells tried to stabilize and BOOM. I never liked using two CR123 ( or RCR123, 16340, or any lithuim, etc.) in series ever in any light, though some companies like “surefire” promotes the practice in some of their lights. Along with the fact there are container loads of these cheap, unsafe knock-off, faulty, ripoff bomb-batteries unloaded here in North America by the ship loads to be bought with no regulation or testing and end up blowing people to little shreds & pieces.
Maybe on the day when they were handing out brains, he was The Last in Line. :bigsmile:
Some factors which could have contributed to the problem…
My guess is that the cells probably tried to equalize each other and there may have additionally been a short causing direct-drive on the output. The tape wrapped around the light helped keep the heat in until something caught on fire, and then it blew apart at the weakest point — the damaged tail threads.
This is a large part of why I avoid serial battery configs, or at least make sure to use protected cells for serial configs. Also why I avoid using damaged hosts, and brush out the inside of new hosts to get rid of any stray metal scraps. And why I don’t use cheap batteries. I also tend to avoid P60 designs, since I don’t trust the thermal transfer from the drop-in to the host.
(the only exceptions I have are a LF L2m w/ UV drop-in and 2x18350 protected cells, and a Convoy M2 w/ MT-G2 and 2x18350 protected cells… neither one ever goes anywhere near my face, and I’ve been thinking for months about replacing one and giving away the other)
One thing we can be certain of, if we believe the details given, the owner is not someone that is cautious and safety first when it comes to the use of his tools.
li ion is risky (Im aware it appears to be LiPo)
series li ion increases that risk
poorly modified or improvised tools increases the risk
popping the tool in your mouth increases the potential damage if the worst case scenario happens.
This was a recipe for disaster. If he had cheap nasty cells it only adds to it, ditto for poorly charged states of batteries, I did not include these as we have no statements to say what brand batteries he was using, or if they were out of sync. But given the above, I wouldnt be surprised if these questions were even unknown to the owner.
The danger of websites such as this, the uninformed and unwilling to read will also source some information from here and act on it half cocked. Its their fault dont get me wrong, but its a reality. Warnings and laws etc will do nothing to help, this stuff is often sourced from OS, and the postage service and couriers are poor law enforcement alternatives. About the only law that will result, is an outright banning on the products, anything else is unworkable and unenforceable with any degree of success. I give you the postage workaround sellers used when li on was banned from transit. There was a long thread on it.
They were labelled as Tenergy, and he used a Tenergy-brand charger. No idea if they were balanced.
after looking at the photos of the light more, it looks like it blew the tail switch boot off and “blow-torched” out the end, along with venting out the front (with enough pressure to blow past the plastic emitter support, and burn the dome off while blowing out the lens at the same time. It was probably like a hobby rocket motor igniting in the mouth.
EDIT* - Just found out from the topic the victim posted himself on CPF just recently. The batteries were “Tenergy LiFePo4” cells, and he was using the supplied Tenergy Charger.
His CPF name is “Subalpine” on CPF.
I believe the explosion caused by the fake battery!
My guess is one discharged cell one charged cell.
From the pictures, (the news link from an earlier post,) you can see that one cell ‘blew’ while the other is intact (but charred). There was a pic with the ‘unexploded’ cell next to an undamaged cell suggesting that he has more than two. Also, if there was a short in the light, would the light still work? He used it for “30s” before it ‘exploded’ so obviously it worked before failing.
Assuming that LiFePO4 cells are capable of venting with flames, I’d assume (like others have previously) that one cell had more charge than the other (possible mix up by a newbie) and the cell with lower capacity vented with flames but did so relatively violently since it was bottled up inside the body of a flashlight and consequently dubbed ‘explosion’ by the media and other personality types.( Yes, I’m being mean! lol) It is also possible that the cells were a different chemistry from what was indicated on the packaging or that the charger malfunctioned or has a large disparity between channels if it has more than one. Another possibility is that the individual mixed different types of cells and doesn’t want to admit fault. It didn’t happen on a plane so I highly doubt any forensic team would give much of a crap… (still being mean. Grrr!)
WRT surefire flashlights and them using primary cells in series, from what I remember, they test cells and match them closely so danger is significantly reduced when buying their cells. WRT individuals buying other primaries and throwing them in lights that use series configurations, the ‘danger’ is increased.
I think this needs to be brought to the attention of Mythbusters, so we can all see some cool hi-res, slo-mo videos of mis-matched series cells venting within a flashlight…. :bigsmile: 
This is a problem in myth busting, they can’t test 1 in a million problems, they can only test cause/effect ones.
…but if they can’t re-produce it, you know they are going to blow it up anyway 
maybe they can use the opportunity to test the detoxifying effects of febreeze 
That is not possible. For that to happen the cells would have to be in parallel and just inserted. Instead one cell tried to reverse the polarity of the other. The opposite from equalize.
Most likely it was one charged and one discharged unprotected cell inserted in series in the flashlight, as has already been suggested. As long as the flashlight is not turned on, everything is fine.
When the flashlight is turned on, the current from the charged cell is used to further discharge the already discharged cell. It will heat up, the voltage fall well below 2.5 volts and it starts to act as a heating element, a resistor. If the charged cell is powerful enough it might even try to reverse the polarity of the discharged cell, as it is further discharged. I suspect that is a pretty sure way to make a battery vent and "explode"...
If someone wants to reproduce this event they can try to short one fully charged cell over one fully discharged (unprotected) cell, with reversed polarities. + to - and - to +. The driver would be in the circuit as well, but if the flashlight was on high/turbo, I assume that the resistance of the driver was pretty low. Use long cables to simulate...
Most likely the flashlight was able to either use one 18650 or two 16340 (or similar). That meant that the flashlight seemed to work almost as normal initially when turned on with one fully charged cell and one discharged cell. But the discharged cell immediatly started to discharge further and heat up.
Oops, you’re right. That was precisely the wrong term for it.