BLF made me aware of the dangers of LI-Ion batteries. I used to use cheap chargers until I got a DMM and noticed on some occasions my batteries were reading 4.4v+. Since then I’ve tossed those chargers and gone with an I4.
I use the cheapest possible cells and chargers, that way, in a flame event, I have not risked too much cash….
At one point I gave trooplewis a hard time for casually dismissing the dangers associated with lithium ion batteries .After hanging around here a long time and realizing almost everyone here " supposed experts " has bought crap batteries ..not to mention the hundreds of millions of the unwashed dimwits who buy ebay lights ,toys ,razors drills,laptops etc....I just never ever hear of someone killing themselves ..probably more people die from swallowing pins than lithium ion batteries.
The sensational news stories about accidents that burn up someones home ,laptop or a cell phone ..even a plane .Are so far and few that I really am beginning to discount the risks and dangers related to batteries .
I suggest people to buy only quality cells ...but even that seems to fall upon deaf ears ...
About the only thing that makes me squeamish these days is when someone starts a thread about a lithium ion battery charger they are building as a project for fun ..Beyond that I think you're pretty safe .it's not like people haven't heard about lithium ion on the forum .Both sides of this issue are chock full of wackos ...the ultra paranoid and the freaky dangerous .
Do a little research ,get a DMM, use good common sense and only buy good batteries ....
Your lights will be brighter
Are there really people out there who are concerned about dieing as a result of a lithium battery incident? Is it truly a mortal fear?
The only thing I am really concerned about is fire damage. In fact it’s not really correct to say that it’s a real concern because I use quality equipment. It would be a real concern (and legitimately so) if I was using cheap chargers and cells made in factories with almost no quality control. In fact it’s the cheap chargers that would concern me the most.
I just make sure I AM AT HOME while charging any li-ion batteries. I usually am since I am the sole caregiver for my father. I also have a nice big printed checklist right next to the door (and 1 in both vehicles as back-up) so before I leave I just go right down the list. I have about a dozen things on my list but the first two are 1. Check stove and 2. Check li-ion battery chargers.
This is a serious subject indeed and should be treated as so,but, THAT IS DAM FUNNY…
DON…
+1
I use my li-ions and my car everyday. 
have you ever tried swallowing a li-ion battery? The 14500s are bad enough, but the 26650s just bring tears to my eyes!
imagine swallowing a 32650 battery
It isn’t the “going in” you should worry about … It’s the “coming out”.
Now that would be an eye-watering (shocking) experience !
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Bingo 
I am still a fairly new li-ion user, but I got the point near the beginning when I discovered how vairable the suckage of the UF 3000mAh red cells was. And I read a lot - here on BLF and elsewhere.
With chemistry already as potentially volatile as li-ion can be, why skimp and raise the odds of making that chemistry angry? Why settle for the very cheapest cells possible?
That said, I have two TFF (from MF) 14500s charging in a TF TR-001 on an end table right next to me at the moment, and I do not fear them in the least. I don’t have a higher priced or higher quality brand in possession as of yet.
There is some psychology at work within us regarding this subject and thread. Fire or explosion? Can it happen? Yes. Will it happen? Odds are, no. But on a psychological level, some fear the worst case enough to take as much precaution possible. Others recognize the possibility of that worst case, but don’t feel that same fear for whatever reason - most likely that idea that the odds are so slim of anything happening, it probably never will happen to them. Then again, I’m sure those who’ve had a worst case scenario thought the same thing.
I think safety protocol is important, yes. But… building a steel safe that can vent toxic gas in the event that a cell erupts seems like overkill to me. I’ve seen the aftermath of motorcycle accidents, and it’s pretty traumatizing and sticks in the mind like a bad dream. But I also ride, and I’ve never felt like wrapping myself in ten layers of Nerf just because accidents are possible.
If I can figure out some very simple and effective way to isolate my charging cells in a safer manner, then I’ll do it. But for now, the close monitoring/touch testing will suffice.
Oh, and I also have jumped out of an airplane, free-handled venomous snakes and scorpions, and dated crazy chicks. What’s life without a little risk?
Really, if none of us liked the idea of a little risk, we’d never even mess with li-ion powered flashlights at all. 
Call me nervous nellie, but I recently bought one of those hobbyist Li-ion charging bags. In retrospect, I probably should have asked about them here before wasting my money...
I NEVER buy, handle, or use any light that has series connected lithium cells (except for the ones that I built with LiFePO4 cells and have a proper battery management/protection system on the cells at all times). Primary CR123 cells are the absolute worst/most dangerous cells to use in series cell lights.
Are you aware that a lag time — after a cell is damaged before a thermal runaway event may start — might be hours or days?
Do you know why the chemistry involved takes hours or days to happen?
Do you believe that if it were dangerous, “they” wouldn’t let it be sold to you?
Would you read a hundred pages to find out what variables are involved, how much is known uncertain and not yet investigated, and what the fire protection folks have found out so far?
Google wants to be your friend. This is quite recent and seems thorough.
http://www.nfpa.org/assets/files/pdf/research/rflithiumionbatterieshazard.pdf
Do you feel lucky? Do ya?
If you do — don’t trust that feeling.
If you think education is expensive, try ignorance.
Don’t rely on me, I’m some guy on a blog.
Look it up.
@lensmanmark: I also use a safety bag. I dont know how it would hold up against a fire, but better be safe than sorry.
@hank: I dont know exactly what you are trying to tell us..
> hank: I dont know exactly …
That’s it exactly. I don’t know.
That hundred page fire protection review doc describes many different ways these cells are being constructed now.
Different materials for the internal membrane — which can get penetrated if (when?) crystals grow after a cell gets damaged.
Different arrangement of the innards; different caps; different vents; much else mentioned in there.
I don’t know exactly what’s in any Li-ion cell I get.
Nobody does, at this point.
And the fire protection folks are just now trying to come up with test procedures for some of the variations.
I’m just sayin’ — to quote Mr. Reagan — ‘Trust, but verify’
And we have no way to verify.
These cells are made for the big companies that bundle them into batteries (a battery means more than a single cell, technically).
I hope the brand name cells sold for individual use are going to be predictable in use over time.
That doesn’t mean “safe” but it means we ought to at least be able to find out what limits to keep them in, and how they behave once damage occurs.
The unbranded, off-label, re-shrink-wrapped ones might be just fine too.
Me, I don’t feel lucky about this stuff and I’m very glad people are reporting what they find out,
and glad the fire prevention folks keep publishing new info.
Every time I search the web, there’s significant new information coming out.
Which means anything I remember is likely outdated.
So I keep looking.
And even using lights with single cells, store them in metal boxes, charge in those fire-containment bags, and check repeatedly.
I’ve only seen one cell vent, long after it was overdischarged and failing to take a charge — dropped it in a metal box to look at later, came back, sometime weeks after, and found the discoloration around the holes on the plus end. It was a RCR2, smallest cell I use.
Well, maybe I’m lucky.
But I’m not going to trust to luck, much.
I started off a few years ago using Ultrafire cells (both protected and unprotected) … I always charged them fully and then stored them fully charged … I used a Trustfire TR-001 and then a Soshine SC-S2 charger and have still got them in case I need them again … I also had a couple of cheap (but very accurate) DMM’s and a very accurate 5.0002V reference to check my meters against.
As my Ultrafires had gradually lost capacity over the years , I decided to replace my old cells with better ones … I now use Panasonic protected 3100mAh’s and a couple of protected XTAR’s , though I still have four of my old Ultrafire cells that are still serviceable … The Ultrafires will probably be disposed of in the next year or so , as I don’t need to use them now.
As an experiment , I made up four of the very cheap charger boards for charging the 18650’s at one amp and I am so pleased with the results that I now use these chargers exclusively instead of my originals … They terminate properly and don’t have a trickle charge (other than a few microamps) … My chargers are powered from a four amp switch-mode 5V PSU fitted with four USB sockets though I usually only charge one or two cells at a time.
I also now have a 6000 count Fluke meter which gives me a reading that is accurate to within one millivolt when checked against my reference.
My Li-Ion batteries are charged on a desk in my study whilst I am working on the computer and it is very easy to simply touch the cells every few minutes just to make sure that the cells don’t heat up … My cheap charger boards don’t take my cells over 4.20V and are usually a couple of millivolts below … They settle another couple of millivolts lower after resting … I always keep my cells fully charged and at room temperature for instant use , so they might not last as long as properly stored cells … My spare cells are kept in a drawer in my desk … All my torches (with batteries fitted) are ready for use too.
If I was convinced that the Li-Ion cells were too dangerous , I wouldn’t use them … I take what I consider to be adequate precautions during charging and I have not (yet) over discharged any Li-Ions … Since all my cells are protected and good makes now , I hope my safety precautions are sufficient … If there is an incident during charging , I will be within two feet of it !
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The risk drops dramaticly when you use a japanese /High quality cell ....
T he way to ensure safety of blf members is just to emphisize that their light will work 80% better and be 62% brighter .
If people need to be scared ...scare them by telling them that their beloved light will sag horribly and output will suck ...
My concern is that if people do start showing up, as the years go by, with fires from these cells,
we could see see the tobacco-company defense used.
Remember? The tobacco argument was that the risks were well known, so anyone damaged knew what the risks were.
I believe the risks are not identified yet — because the national fire prevention document linked above says
—- they haven’t identified the risks yet,
—- they don’t know how the cells are constructed yet, and
—- they don’t have a procedure yet for testing how they perform and how to handle fires.
Keep that bucket of sand handy.
The use of one micro charger per cell, charging them right in front of you, and touching them to check the temperature, is a conservative approach.