Did I kill it? 14500 li-ion!

Well I took my first ride home tonight with my 14500 li-ion powered Q5 modded DX light. Been running it for a long time on NiMH but wanted the extra juice of li-ion (more Vin = more I to led)...

Anyways, they aren't fancy cells just Trustfire 900mAh protected cells from DX. Been topped up a few times but this was the longest burn this cell has seen. Maybe about 20 minutes from on until it went out. Heat was not an issue as I cycle about 17-20mph and its below freezing outside.

I'm only worried because: 1) it went out in about 20minutes, thats well over 2C discharge 2) its been over 45 minutes since it went out and the cell is still reading 0V


So what do ya'all think, did I kill it or has the protection not reset? Should I throw it on the charger or wait? I don't particularly feel like seeing it shoot fire tonight...

if its protected many batteries will not go back on untill you put it on a charge (of some sort at least).
some will keep resetting, but the trend now is to shut it off, and not continue once it reaches the set low voltage.
putting them to some sort of charge resets it.

many (not just some) single cell, low voltage lights will overdrive with a li-ion , makes them nice and bright, but cuts into runtime a lot.
and Most of these will also run much more current through than they do with a 1.5V type battery, even after the overdrive ends.
that and the quality of the cell is why you can get really cruddy runtimes.
a bit of that will get better after a few cycles , but not much.

umm so in short, i doubt that you have any sort of problem, there are many factors. Put it on the charger and then read the voltage.

The protection circuit kicked in, should charge up fine, probably wasn't fully charged, or the light is drawing more current than the protection circuit will allow.

Yeah I know they aren't the best cells, but it was just a "toe in the water" to see if 14500 was worth getting into... Which it certainly is! But thats another topic, eh?

Well I'll toss it on the charge for a few and see if it registers. If I ever get my minimag hotwire figured out I'll have to pick up a couple AW cells for both lights....



Edit: Yup, after literally 10 seconds on the WF-139 charger its reading 3.91V (no load)... Guess the light might be over driving a little. Light draws 3.92V 0.94A from a fully chagred 14500 battery... Figure the driver was giving almost 4.2V to the Q5 with NiMH (IIRC) this would mean I'm driving the led at about .877A in an ideal world... Cheap driver so I'll sac 30% of the watts as an overestimate leaving .614A to the led. Hmm .94A isn't really that much is it? Its just barely above 1C if you go by rated capacity (which is obviously not so accurate), but probably closed to 2.5C which maybe not so good?

Best to put LiIon's back on charger as soon as you notice low voltage. The sooner the better. All of mine have bounced back as soon as they hit the charger.

Bill

The protection circuit probably kicked in from low voltage rather than over current, but I don't know what current they set those at.

i tested these trustfires for load

i pulled out .67 amps on a full one after 38 minutes it went into protectionmode
that is 38/60 *670=424maH(900maH advertised)

did the same with an AW14500
i pulled out .67 amps on a full one after 47 minutes it went into protectionmode
that is 47/60 *670=524maH(750maH advertised)

i must say these were new ones which were only charged a couple of times
i do not know if these needed break in or not.


if your light draws 0,94 amps it should last about 27 minutes accoording to my reference cells

hey, I posted this elsewhere to get some more exposure, but I'm having a 14500 issue that I can't figure out for the life of me. I've been using them for a couple days now in my Nitecore, and all of a sudden the light gave me a low voltage warning, so I popped it out and changed it to my other 14500. After a couple minutes of use, same thing. So, I figure they need to be charged. I popped them on my charger (ultrafire wf139), and within 2 minutes, they registered a full charge. Now, I don't have a DMM at the house, but that can't be right. I popped them back in the Nitecore, same thing. I'm hopelessly lost. What the hell is going on here? Get back to me when you get a chance. I'd appreciate it, as if these cells are dead, I'll be pissed. Thanks in advance.

Cheers!

Samson

the only way to know if the cell is indeed dead is either

buy a DMM and measure the voltage or
put the 14500 in a light without protection and see how long the charge will last.

other options are put the ndi in a 50% mode so it will not draw to much current and see how it will react
if this is ok but on 100% it will flash low warning than i think the cell is probably defective(or you ndi but better not think of that)

Well, I dug out my AMM and I'm pretty good at reading it. The cells show up as roughly 4.2 freshly topped off. The bad news is I need to replace the fuse in my meter before I can check the cell later. I want to see what the voltage drop is once the warning goes off on the NDI and the protection kicks in. At least that will give me a little more information, I hope. I'd REALLY hate to think that my NDI is killing cells, or worse, defective. Ideas?

samson722 said:

Well, I dug out my AMM and I'm pretty good at reading it. The cells show up as roughly 4.2 freshly topped off. The bad news is I need to replace the fuse in my meter before I can check the cell later. I want to see what the voltage drop is once the warning goes off on the NDI and the protection kicks in. At least that will give me a little more information, I hope. I'd REALLY hate to think that my NDI is killing cells, or worse, defective. Ideas?

Click to expand...

On a side note, I'm wondering if it's because the cells haven't quite broken in yet. They've only charge twice for ~2 hrs. Could this be part of the problem? LMK, thanks!

ETA: OK, roughly 20 minutes or so at 50% and my NDI is yelling at me, with that damned low voltage warning. I'm getting sick of this...

Regards,

Samson

like i said

run the ndi at 50%

if the light holds the battery probably is ok
if not the voltage drop is caused by a bad cell

samson722 said:

On a side note, I'm wondering if it's because the cells haven't quite broken in yet. They've only charge twice for ~2 hrs. Could this be part of the problem? LMK, thanks!

Regards,

Samson

Click to expand...

gravityz said:

like i said

run the ndi at 50%

if the light holds the battery probably is ok
if not the voltage drop is caused by a bad cell

Click to expand...

it sounds like he might have a bad cell, high resistance, which would be hard to check with a voltmeter without a bit of load.

that would mean i have two bad cells... what are the chances?

samson722 said:

that would mean i have two bad cells... what are the chances?

Click to expand...

oops, i mis read.
check the cells with a 10ohm fat resister across them, and a voltmeter.
or put any kind of load across and test it. there is many ways to do that.
you can get a 10ohm resister from radio shack (the big fat one 5W or 10W)
you could use some 4-6V incadescent bulb , a 6v would dull glow, but still work to put a load on
or a resistered led .
some way to run a discharge on your desk there where you can see what occurs.

if i remember right a nightcore can fully discharge a 14500 that is NOT PROTECTED. if you have unprotected cells, then chances would be good that both are ruined. IF you ran them to depletion in that light.
(cells ruined in this manner are very dangerous to charge)

so are the ones you have protected?

hmm that is all i can think of till you see what happens when you discharge it.
a connection issue in the light doesnt make sence, nor does a protection disconnect, because the low voltage indication wouldnt occur.

is it getting warmer on the charger? because waste heat when charging is an indication that the charge is not being accepted. also not likly because you have a solid 4.2V reading after charge.

they're protected 14500s from AW. they're staying cool on the charger. i'll pick up a dummy load from my electronics supplier and grab a DMM from the shop and check it out. i'll hope that it's the cells at the worst. i would hate to think my NDI is dead. that would suck.

yes but when you draw less amps from a bad cell the voltage still drops

if he puts his ndi in 50% and see what happens we know for sure
see if it works up to a point were the currentdraw is to high for the cell
if it drops out on low it is the cell which is bad.

VidPro said:

it sounds like he might have a bad cell, high resistance, which would be hard to check with a voltmeter without a bit of load.

Click to expand...

Should I consider it more evidence of bad cells if my NDI works peachy with regular 1.5v alkies?

Hello Samson,

So, what happened when you ran at 50%?

Tom

i do not think he knows that his light can be put from 1%-100%

i have asked hime several times and he keeps on asking other questions

if he is asking for help he better do what people suggest otherwise this will be one long thread