TM26 comes on in suitcase! battery damage/reliability

[DimNoMore]

Boy was I stupid! I put my fairly new Nitecore TM26 into a loosely packed overnight bag with some clothes. It got put in the back of a pickup for a 90 min drive in near 100 degree south TX late afternoon heat. At destination, bag stays in back of truck till about 9pm. Getting out the bag to show my brother-in-law my cool flashlight, upzipping the bag the light was ON, and in HIGH (4000 lumen) mode!!!! The surrounding clothes were very hot, but nothing melted/smoking. The body of the light was too hot to handle. I turned it off and it remained too hot to handle for over an hour. Next morning quick function test showed batteries almost dead, but it cycled thru all the lumen settings, including 4000. All 4 of the expensive Nitecore brand 3400mah protected batteries' outer yellow wrapping had split down the middle, revealing a green wrapper underneath, NCR18650B being visible on one of them in the "wrapper gap" that is uniformly about 1/4" wide. The yellow Nitecore wrapper is still tightly adhering to the batteries, and the split seems to be opposite of the side of the battery where the strip connects the circuit boards on each end of the battery. I also noticed that yellow Nitecore wrapper says "made in China": I assume that refers to them taking Jap Panasonic unprotected flattops and turning them into the current config by adding the protection, the connecting strip, and wrapping them in the Nitecore wrapper. The cells are charging on my Nitecore i4 charger and seem to be charging normally, all being up to 2 flashing lights after about 2 hrs charging; I **assume they will go to full charge at 3 steady lights with more time.


Questions:

1) Why didn't the protection circuitry of the light itself or the batteries shut off operation after a time at such high heat?
2) There is no visible damage to the light. Any LIKELHOOD this caused some kind of damage that will manifest later?
3) Any LIKELHOOD this caused some kind of damage to the batteries, assuming they complete their charge?

I can envision a lot of scenarios where this could have ended VERY badly; learn from my stupidity. I will never again put this TM26 in any container without first employing the lockout feature AND backing off the threads a few turns to prevent contact for the cells.


Thanks in advance for any advice/commentary.

 

[DimNoMore]

I omitted the fact that the bag was packed at about 5pm; in theory, the light could have been on as soon as the bag was closed up. However, if so, it must have cycled thru various power modes as no way it could have been in 4000 mode for more than a few minutes without stepping down in power.

 

[NoNotAgain]

The TM26 couldn't have been on for a long time on the 4000 lumen setting as the heat of operation would have caused the light to step down after it got warm unless there was a major malfunction.

Being tightly packed inside your luggage with clothing surrounding light light is what caused all of the heat build up. The cell wrapper splitting is due to both heat and having reached the maximum that the battery would allow for.

I had a TM15 activated in a coat pocket in the holster. When found, it was about and hour and a half from the start of the trip, so it was on for less than that time. The light started melting the end of the holster. After that occurrence, i physically locked the light out.

Recharge your battery, install into the light and see what voltage is displayed. If in doubt, set those batteries on the side until you can further test.

 

[reppans]

...Getting out the bag to show my brother-in-law my cool flashlight, upzipping the bag the light was ON, and in HIGH (4000 lumen) mode!!!! The surrounding clothes were very hot, but nothing melted/smoking. The body of the light was too hot to handle. I turned it off and it remained too hot to handle for over an hour. Next morning quick function test showed batteries almost dead, but it cycled thru all the lumen settings, including 4000. All 4 of the expensive Nitecore brand 3400mah protected batteries' outer yellow wrapping had split down the middle, revealing a green wrapper underneath.....

...I can envision a lot of scenarios where this could have ended VERY badly...

No offense to the OP, but this stuff scares the crap out of me every time I board an airplane. I know TSA/airline rules limits quantities and require lithium cells to accompany the passenger in the cabin (better, but not hugely), but does the TSA actually look for flashlights in checked baggage?

 

[NoNotAgain]

TSA looks for anything that is dense in your checked luggage. A flashlight of this size would be visible and depending on the screener may or may not get a secondary look.

Attach a few wires to the light, and they'll have your bag ripped open before you can say, oops!

I had a luggage alarm that the TSA destroyed. Looked like a pager with a small stereo plug and a piece of paracord. Open the case , plug was removed and this little monster yelped at over 100 dB. Two ways to shut it off, replug the stereo plug or kill it. They killed it. They didn't even give me the standard TSA, we opened your luggage note.

 

[yoyoman]

I know the rules but I once packed IMR 18650 cells in my check-in by mistake. About 6 of them. Each cell was wrapped in a small plastic bag and put in a foam tube. I meant to put the tubes in my carry-on bag. In the last minute rush, they went into the check-in bag. Transatlantic flight. Never checked by TSA. We had 4 bags in total and 2 others were checked. But not this one. Much more careful after this incident.

 

[more_vampires]

Op, you were lucky, you were worried, did you remember to check voltages before charging? You said yourself some questions on protection circuits.

My 2 coppers is to never charge lions (supposedly protected) that have been drawn down past 2.5-2.6v.

Protection should have kicked in by then, heat can disable protection. Extreme heat, too hot to touch? This can do a lot of weird stuff to electronics.

Glad you are ok and your lions didn't vent with flame upon charging.

Alarmist? No, realist. The last thing we need is yet another mishap. Glad you are ok, op!

 

[DimNoMore]

Update: I charged for 2 hrs last night, they got to 2 blinking lights in i4 charger. Resumed this morning and 5 hours on the charger now and no movement past 2 blinking lights on charger. I took them off, installed in TM26, and they read 4.0 volts and a full charge battery symbol. Cycled thru all functions just fine, checked voltage and its down to 3.96 and one bar of the battery charge indicator went dark. I am getting 3.99 on my voltmeter on all cells.


What think battery pros? Continue to recharge & expect decent future performance, or did I screw em up?


Thanks for comments and yeah, I was lucky....sure feel stupid not to even think to employ the lockout feature on the button. Got in a rush to leave!

 

[NoNotAgain]

Personally I think they're fine, but I wouldn't use them until the voltage was verified with a vom.
Not uncommon to see the .04 voltage drop you reported.
Before charging again, verify voltages between all of the cells. If they vary by more than .1 volts, they my be trash.
I believe that bay 1 and 3 charge at .75 amps, so if you only charge using these two bays will change the cells within 4-6 hours. The i4 charger isn't the fastest charger. I would expect 10-12 hours to recharge from fully depleted to 4.15 volts.

 

[Pöbel]

better be safe than sorry and get new cells.

probably the cells will work and just their life expectancy went down alot - but cells are not that expensive to take any risk

with those new high powered lights we have to rethink our wayy of handling of flashlights

always lock out during transport

 

[WalkIntoTheLight]

How did it stay in turbo so long as to take it more than an hour to cool down? Besides checking the batteries, you should make sure the light is stepping down like it should. If it's not, you could be causing the LED to age prematurely.

 

[FRITZHID]

better be safe than sorry and get new cells.

probably the cells will work and just their life expectancy went down alot - but cells are not that expensive to take any risk

with those new high powered lights we have to rethink our wayy of handling of flashlights

always lock out during transport

+100%!
These cells, even in the hands of competent users, can be and are dangerous. No need to risk life, limb and property over a few bucks. We've all seen/read the horror stories of lights going boom in people's hands and personally, that's the last thing I want to hold onto.... A ticking bomb.

 

[Pöbel]

How did it stay in turbo so long as to take it more than an hour to cool down? Besides checking the batteries, you should make sure the light is stepping down like it should. If it's not, you could be causing the LED to age prematurely.

it doesn't have to stay on turbo. wrap a light with no way for heat to escape and even levels below turbo can generate enough heat over a certain amount of time

 

[WalkIntoTheLight]

it doesn't have to stay on turbo. wrap a light with no way for heat to escape and even levels below turbo can generate enough heat over a certain amount of time

He said when he unwrapped it, it was on 4000 lumens.

 

[DimNoMore]

i4 finally completed the charge to 3 steady lights by 2pm today, total of +/-9 hrs. I took them off and they all measured 4.17 on vom / 4.20 in the TM just as they did the first time I put them in after a full charge. Maybe I got by with out damage to anything except the Nitecore yellow shrinkwrap around the cells. Those things were NOT cheap either.
Thanks to all who replied and any yet to come. Lesson learned!

 

[d88]

I always keep my TM26 locked out by unscrewing the tailcap. With the electronic switch on it, it's far too easy too switch on.

As for the 4000 lumens remaining on , the thermal regulation usually kicks in on mine after around 5 mins @ around 60C and steps down accordingly. I'd check it by letting it run on full output for a while and see what happens. If the ATR function does not work, then you may have a faulty light, if it does kick in then you know the light was probably only on for a few minutes

 

[more_vampires]

i4 finally completed the charge to 3 steady lights by 2pm today, total of +/-9 hrs. I took them off and they all measured 4.17 on vom / 4.20 in the TM just as they did the first time I put them in after a full charge. Maybe I got by with out damage to anything except the Nitecore yellow shrinkwrap around the cells. Those things were NOT cheap either.
Thanks to all who replied and any yet to come. Lesson learned!

Wouldn't hurt to do a capacity test on a battery analyzer. Were this my setup, I'd do a full cycle test on my Opus. If the cells have mismatched capacity, I'd split the set and run them in single cell lights only.