@scaru: We cant be mad at little crying babies, so we dont really have much of a choice. :)
The good thing coming from scaru's experience is that, as of today, we will be removing all batteries from flashlights when travelling especially if they are li-ion's.
Better safe than sorry right?
Yep, I know I will. I had originally had them in a pill bottle that fits three of them perfectly but decided to put them in the light. Definitely a big mistake.
+1.
Just like I learned to turn off / hibernate my laptop (instead of using the sleep mode) after it woke up by itself in the laptop bag. :X
You and all the people in the plane definetly got a break from above, did you check for heat damage to the leds? I would discard the zero volt cell for safety reasons and keep an eye on the other ones.
Protected batteries from now on?
I wouldn’t actually go with something like just a baggie to separate them. Li-ion don’t do well after physical damage either and the combination of TSA fumbling and trained-by-gorillas baggage handlers presents risks too. That physical damage can start a fire as surely as overdischarge of slightly off balance cells. There are some pretty cheap plastic cases at some of the usual budget dealers that would let you isolate them from the light being turned on and offer protection from crushing.
These plastic cases don't offer any security against crushing. If something can crush a cell, it also can crush plastic. But they will keep the cells from touching.
I'd get rid of that pesky Dry
I'll take it ...
pm sent :P
Nothing the least bit ironic about the TSA taking something harmless and turning it into a bomb. :~
You, sir, are one lucky SOB! 
Maybe I’m just being paranoid, but can Lithium-ion batteries cause a fire on a plane?
Are lithium-ion batteries the next threat to airline safety?
“When a lithium battery short-circuits or overheats, it can catch fire or explode. The fire it causes may not be as easy to extinguish as a normal combustion fire.”
http://www.usatoday.com/money/industries/travel/2010-08-16-airlinebatteries16_CV_N.htm
TSA information about batteries:
http://www.tsa.gov/travelers/airtravel/assistant/batteries.shtm
Whew, lucky break. Glad you're ok.
On the plus side, we got an example why unprotected cells are not safe in serial configuration. This was so close! The 0V was reverse charging, lucky that scaru was lucky! My stomach was turning inside out reading the post.
Time to get a King. Parallel, no reverse charge, withstand Hi until low batt, doesn't kill batteries permanently, can use unprotected, can lockout at 1/8 turn, no need tapes 
and even with all that SAME SIZE SAME OUTPUT.
scaru, you must be Irish. As in, “luck of the Irish” (it’s a good thing). Ban Lithium batteries on airplanes? That means no cell phones, no laptops or tablets, no ipods and the like and certainly no flashlights sporting high end batteries.
Glad to hear no harm done! We can chalk this up to another lesson learned with no harm done. No offense but why were you using un-protected batts in a multiple battery (series) light? I would be terrified!
Keith
The main problem is you cannot have lion batteries in luggage unless they are installed in something.
Would it not be better to tape the individual cells to prevent the circuit forming? Ie wrap positive to negative or is there not the space in the host?
How about making a bare “host” out of grp tube or something to carry the cells? Although I suppose that could be mistaken for some sort of pipe bomb….
That is scary stuff scaru. If a fire and started in the cargo hold……
You are one lucky person. Better to pack the light unloaded and the cells in bubble wrap and box.
Any high drain light for that matter. And the TSA is not very pro-active to this specific medley of voltage and extreme battery consumption. UPSP is
Fortunately I don’t fly much anymore, but it chaps my arse that some idiot meddles with technology and perhaps creates a TRUE hazard to a lot of people, with little to no consequence.
I fear part of the problem is the trouble hiring people intelligent enough to understand what they are doing, within the budget available.
I would be tempted to pen a formal complaint, detailing the events and the possible repercussions, it seems someone inspected the light, probably powered it up, went “wow look at that” and promptly gave it no more thought.
I’d be tempted, but then I wouldn’t because the knee jerk reaction would probably be to ban li ion cells…. :weary: