18650 problem. Please advise me

Hi, I bought 2 TF flame 18650 off DX.

I put them into my 3T6 and the torch did not light up. I immediately realized I put the battery in the wrong direction. When I put it in the right direction, I was surprised to find that the 18650 became very hot. Fortunately, the torch light up and I was happy with the performance.

Now when I am about to charge, I realised one battery indicator on my charger does not light up. I used a multimeter to test and found that one of the battery measured 4.0v and another 2.4v.

Is the 2.4v battery spoilt?

It might be ok if you put it in a cheap charger and let it charger for a bit, but keep monitoring it! Failing that leave it 24 hrs and the voltage might come back up.


Is the battery defective? Or is it normal?

Yes. Dump it. Thats what you should have done when it got hot in the first place. What were you thinking?

I guess it got hot because I inserted it in the wrong way and that may have damaged the battery

It depends, personally I have 4 trustfire flames and they have been pretty good, but I bought them when I first got into 18650’s. Now I would buy nothing but Sanyo 2600 cells and they are only $2 a pair more.

Leave it 24 hours and see if the voltage comes back up, if it does just keep your eye on it. It might be fine.


Ok guys, you don't really advise a beginner to take a risk with a cell worth 4$ that got hot?

Is it 2.4v a reason for refund in DX? I will follow advice to buy better 18650 from now on! And for the time being is it okay to use both in my 3T6 torch? Or will it be dangerous?

No don’t use them together! Yes get a refund and buy some Sanyo’s at Fasttech for $10.58


If you think you accidentally damaged cell how you are going to refund it?

I recommend you be careful with li-ions and use brand cells like Samsung, Sanyo, Panasonic…

First of all: Get rid of that cell. [You should consider yourself lucky! It could have exploded your flashlight!]

Some pieces of advice:
- Buy only quality cells
- Always use "matched" cells in multi-cell lights:
- Mark the pairs, straight out of the package
- Check voltage before inserting them to your 3T6 (if difference is more than 0.1V => don't use that pair in multi-cell)
- Check voltage after use (again: if diff > 0.1V => use only in single cell)
- Always check the voltage difference before inserting the batteries

thanks all for your advice. Maybe it the PCB protection that prevented it from exploding when I place it the wrong way. And now the PCB board is fried.

Hmmm I do not know whether inserting it the wrong way will damage the battery

Is it because the PCB has been tripped? Or is it because the battery is originally damaged?

I do not have any protected batteries, honestly, I do not trust a pcb, especially pcbs of cheap batteries.

If it shows 2.4V I think, it is because battery damaged so you should dispose that battery.

Show us a picture of that battery and we can tell you if its protected. A lot of cells claim to be protected but arent.

If it got hot because of the PCB, only the thin metal wire would have been hot and usually melted through the shrink wrap.

1. It’s great to buy budget flashlights, but personally I think it’s dumb to buy budget li-ion batteries. For the batteries, it’s much wiser to go for high quality cells. Poor qualities batteries can turn your flashlight into a hand grenade. You don’t want your light exploding in your hand.

2. Always used matched cells in multi-cell lights. This rule applies to just about every multi-cell light out there. If you don’t use matched cells you could potentially have a situation where one cell runs out before the others and then gets reversed charged by the more full cell. This reverse charging can cause the cell to vent and your light to explode.

3. There is currently only one multi li-ion cell light that is safe to use non-matched cells. That light is the Zebralight s6330. That light is safe because each battery powers its own emitter and is on a completely separate circuit from the other batteries. It’s the equivalent of having 3 single-cell flashlights held together by a rubber band, but using a single switch.

The battery cost like $5. It’s not worth risking having your face blown off. Get rid of it.


In my experience, even a short lasting 5 seconds will turn an 18650 into a red hot thing of danger.


Remember that inside these cells is not just packed chemicals. They are in a VERY thin plastic bag and rolled up into a cylinder. It doesn’t take much heat to breach that plastic bag, and once that happens ALL bets are off. Once air gets into the mixture, you can have big problems. Once you add a charging current to to that, it is even a bigger risk.

And since we don’t have xray eyes, we cannot see inside to see what happened.

PLEASE stop using it and put it outside for a couple weeks, away from the house, to make sure that it’s stable. And then what?

Which brings up a problem, what the heck do you do with potentially dangerous breached cells like this? Doesn’t seem smart to put them in a Home Depot battery recycle bin and hope they don’t vent with flames in a couple days. Fortunately, I have not faced this issue yet (there was nothing left excpet little black grains when my li-ion blew up). What do you do with the cells??

For Lipos (Very similar compounds w/different housings) discharge them slowly (If possible using a smart-charger/cell drainer) but don’t risk anything and drop them in a salt water solution. The lithium will react slowly with the water and eventually wear away.

Afterwards you can send the cell out for recycling but there shouldn’t be anything harmful in it that would prevent you from throwing it out (However the ALU and other parts can be recycled). Should probably drain the water v reaching in too.

Lithium isn’t an inherently deadly chemical (However it does react w/water/moisture to cause “fire”) although non properly administered quantities can case death in very small amounts. Don’t do drugs, don’t do lithium, but the batteries are ok.

www.thunderpowerrc.com/PDF/DISPOSAL-OF-LIPO-BATTERIES.pdf”: www.thunderpowerrc.com/PDF/DISPOSAL-OF-LIPO-BATTERIES.pdf

I’ve got some Lion’s that I’ll have to do this too at some point, can’t just leave em laying around. If anything really bad happens then I’ll report back.

It isn’t a good idea to just turn in charged cells for recycling or disposal in landfills (they could start a fire) so it’s best to neutralize them yourself (Or have someone else do it) then junk em.

And that cell sounds pretty dead, junk it soon. Lixx’s are so cheap anymore that I don’t even bother too much w/reviving cells; its a PITA and most of the time it doesn’t work. Buy a new cell, only use matched batteries in multi cell use.

I’d like to mention that putting one cell in reverse in a two series cell light will not cause damage to the cells. In fact, I intentionally install a cell backwards in my two series cell lights to ensure “battery lockout” when I’m carrying the light in a manner where it could accidentally turn on (in a backpack, for example).

Someone on here put their cells in salt water to completely and fully drain them