Taking the fun out of hi-performance flashlights~

This forum will put the fear of God into you


Has anyone here had any similar experiences with 18650 or CR123 batteries venting, exploding, or otherwise acting in suspicious ways?

You would think that since we use "cheap" flashlights (and probably cheap batteries too) we would be more susceptible to this kind of thing.

Almost makes me want to take al the batteries out of my flashlights when I am not actually using them, but that would be a royal PITA to do.


I heard a report about a chevy volt catching a garage on fire today. I do watch my batteries closely when charging, but just being careful and common sense go along way.

I must first say, I am not an expert but this is what I have read:
If you do things the right way you should not fear anything.
You have to read batteries maximum discharge current. In some Lithium batteries this is just 500mA. I you discharge them at higher rates you are on risk. Some batteries have something called, if I am not mistaken, an over temperature protection at the positive end. Some don’t. You should read battery specs before using them.
A long time ago I bought some Tenergy Lithium batteries I never used because the maximum current was 500mA and according to some people didn’t have the thermal protection. I wanted to use them inside my Fenix P2D which was going to pull ~1000mA. which was out of batteries specs.
If you are using rechargeable Li-Ion batteries you must take care with maximum discharge voltage (the lowest voltage the battery could reach)which under high loads shouldn’t be lower than 2.7 volts and under no load shouldn’t be lower than 3.5 volts. Maximum discharge current (the maximum current when i use) which usually is 2C (twice the battery capacity). Charge current shouldn’t exceed 0.7C. If you have a 2000mAh Li-Ion battery, it should not be charger at a rate higher than 1400mA. Some people do 2C while charging and they have been lucky since nothing has happened.
Finally, you should never short circuit batteries and you should be very careful your flashlight will not put the battery in short or it is very likely that it will vent/explode probably with fire.

What is really scary is that some of the stuff happened when the flashlight was off, and unattended.

I don't really have a way of testing cells to see if they are over or under charged, maybe I need to invest in a multi-meter.

Here is ANOTHER related question for you flashaholics. Do you have "good" battery chargers, or the typically cheap Chinese ones.

I have two and they both look like this

I have to admit i have a budget charger and these batteries (one user from CPF has a bad experience with these battery). I'm using them for one year and nothing happened so far. Everybody know that lithium battery are dangerous if not used in the right way. The rules are always the same:

- Never leave battery unattended while they're charging

- If you know you will not use a flashlight for a long time, take out batteries

- If you can, store them in a box that can prevent from damage if something happen

- Respect the technical specification of the batteries

- Never short them

I can go on for an hour but i think many of us already know the basic rules for avoid accident. I think also we can assume that rarely an accident could happen also if you take care of every single rules...

I've had about a dozen lithium cells die on me. None of them have failed dramatically.

I have fed 240V AC to one to see what would happen. When I was 100m upwind and there were no people within a kilometre. It did burn - but not dramatically. Produced a lot of smoke that I was careful not to go near and left some rather nasty stuff that I knew how to deal with safely (In a previous career I was a chemist)

Lithium ion cells can do Bad Things, but follow the advice in the previous post and it is very, very unlikely to happen to you.

If you are aware that they can do Bad Things if maltreated, they are unlikely to do Bad Things to you.

Hey Don, that almost sounds like "ignorance is bliss." I have to confess, I don't stand in my garage for 3 hours while the batteries are charging. I may periodically stick my head in there but that's about the extent of my preventive measures. Do you guys eyeball the charger during the entire cycle? As some here in Texas would say - that's no bueno. My garage is insulated but this will be our first summer here in this house so I'm sure it will get pretty warm. After reading all the warnings, I didn't feel comfortable bringing the charger & batteries inside. Would it be "safer" to have them inside where it's air conditioned to stay cooler?

I've started checking every five minutes after I burned myself on a cell that was mysteriously being charged at an absurdly high rate......

I charge my 18650s in the kitchen. Bad? I usually check the voltage going on and coming off the charger and I never let them just sit there charged with a green light. I pull them off right away.

<don't follow my advice - not an expert> A lot of the bad things that happen to lion batteries is in multiple cell applications where one cell is discharged significantly relative to the other cell or a single cell is discharged too much. And then there's heat, of course.


I don't have much experience yet, but I only charge when I'm around. Since Li-ion doesn't need to be charged in one go, I just unplug when I leave. I also leave it in the middle of a tile floor, so any venting won't reach walls or anything. And I have a jug of water nearby. Has anyone here had one explode or vent (not on purpose)?

A jug of water may not be best for an electrical fire, but it would help the surroundings if they were in danger of catching fire or damage from the burning cell.

I only charge mine when I am near, and I make sure they are in the open, not near any walls/furniture etc.

I also like to stick to single cell lights with my li-ions (except for my TK35). My romisen rc-t6 and palight rarely get used unfortunately.

Hey JB, fellow texan!

I've never brought my charger inside, sits on the workbench in my garage. My workbench section has a plate steel topper, a nearby fire alarm & extinguisher, so I'm not too worried about any fires if it does blow. And have charged many times when its 100 degrees outside, doesn't seem to care. I don't babysit it, but do keep my eye out when the green lite come on & remove them & check voltages. My $0.02, but beware I'm far from any expert!

I have mine on about a 3" thick wooden workbench as well. The floor is tiled so I might move the charger down to the floor. I've been considering a fire extenguisher for the garage and pray that I never need to use it but I may go ahead and pick one up. Thanks for the feedback considering our weather is very similar. You typically have more humidity down there but I'm originally from south Louisiana so I know humidity.

Please don't consider it .... just do it!

I've had to use mine several times over the years. First, and most serious by far, was a grease fire on the kitchen stove. A few years later had a paper waste basket in the garage must have emptied an ashtray in that had a smoldering butt. Last year I was stupid, trying to start a troublesome weed wacker with starting spray & shot the hot muffler by accident, vapors flashed & caught some gas residue on fire.

The waste basket & weed wacker incidents were minor & could have easily been taken care of. But I hate to think what would have happened without an extinguisher on that grease fire!

also lots of fun to squirt the neighbors cat when he wanders over

...off my soapbox

The problem is if a cells goes very bad and decided to ignite, you can't put it out with water as they rather inconviniently supply their own oxygen.

I think the chances of your self exploding is rather less than the chances of you spilling that jug of water on something you shouldn't :P

When you're using a hobby charger you can put the battery in a fire proof bag like one of these >Liposack< but that's not really an option with an ordinary charger as you wouldn't realy want to put the charger in it as that might cause it to over heat.

I recently bought an Xtar MP1 charger for £4-5 of eBay - >Xtar MP1< as I wanted something small I could pop in a bag when travelling.

It's powered via USB (although I use it with a mains-USB adapter) and charges at a fixed rate of 500ma, so it's not very quick on a 2400mah cell.

I've tested 5or6 cells through it now and it's seems to work flawlessly.

I've found my self using it instead of my hobby charger, mostly because it's so small I don't need to clear a space for it and it's up and charging faster than I can plug the other charger in...

I have a cheap DX charger as well. I charge my batteries on the kitchen counter; the main living area is located on the opposite side of this bar so I'm always in the same room. That way, if anything goes wrong, I'll definitely smell it. I have a fire extinguisher handy as well since it's in the kitchen. So far, no issues. All I have to use are the Gray Trustfires from DX and the pink Samsung cells salvaged from Dell laptop battery packs and so far, no catastrophic failures!

I also use DX Trust-it-will-put-you-on-fire chargers in my home office but always charge Lion batteries while I am working on my PC. If I am going to leave the house, I remove the chargers from power supply and the batteries from the charger.

On the safety side, I have two electricity safe fire extinguishers (total 6kg) just in this room...

Am I feeling safe? No! In my office I also keep about 50 Lion batteries, two laptops and a UPS... This room is in the middle of the house and you must pass outside of it if you want to leave the house. So if this room is on big fire that passed the door (or the door was open), you can't leave the house... So I am searching for a safe place to keep my Lion batteries...

If I was afraid of charging lithium ion batteries I'd be charging them in the fireplace in a fireproof box .

You always wanna be near by when you're charging that way when they go off like a bomb you can experiance the full Richard Pryor experiance ..

"people get out of your way ...When you're on fire "

After reading this thread, I had a nightmare about 2 of my 18650 cells combusting. Bah lol. Now I am scared to use my li-ions lol.