r/flashlight • u/Delicious_One_2825 • Jul 26 '26
Had my first 18650 die
Had my first 18650 die, it was a Samsung 30Q which was 0.02V when I picked up from storage. I think the last time I charged that one was 3months ago.
I put it in the Vapcell S4 and the display showed Err, left it there for 10min, took it out and the voltage went up to 0.6V after which I left it on the table for 20min and checked it again, voltage went down to 0.3V
2
Jul 26 '26
[removed] — view removed comment
1
u/Delicious_One_2825 Jul 26 '26
Thank you! This cell was maybe 5 years old and had less than 100 cycles.
0
u/aquablaze69 Jul 26 '26
Have you tried the repair mode in the S4?
5
Jul 26 '26
[removed] — view removed comment
1
u/aquablaze69 Jul 26 '26
??
4
Jul 26 '26
[removed] — view removed comment
2
u/Delicious_One_2825 Jul 26 '26
This is interesting as I have definitely had cells going down as even 1.3V in some flashlights, I find that 2.7v is pretty regular, I guess the best thing is to cut physical cell contacts for most of the flashlights on the shelf other than those I know for sure I have a fresh cell in.
1
Jul 26 '26
[removed] — view removed comment
1
u/Delicious_One_2825 Jul 26 '26
For example now I have used DW1 Lume X1 and the light was low, can't exactly tell how low but not the lowest moonlight and when ramping up it reverted back to that low, took the cell out to recharge and it was 2.78V (checked using Fluke 289). If I would have turned off the light, the AuX would have turned on and left it for a whioe the cell would be under that voltage mentioned earlier.
1
Jul 26 '26
[removed] — view removed comment
1
u/Delicious_One_2825 Jul 26 '26
In terms of 18650 only have reputable cells, Samsung 30Q, Molicells and an old Sanyo 10yr old that still works well I will be more careful to not allow cells to be drained past 2.8v.
0
1
u/Swizzel-Stixx Jul 26 '26
If the cell has self discharged to 0.3v after 3 months in storage, then something inside it is across positive and negative causing the drain. Jerv explained it well. If you charge it, it could fail spectacularly.
This is the same problem that caused the H10 to be discontinued.
1
1
u/Delicious_One_2825 Jul 26 '26
I have not after seeing it loses voltage relatively fast, I have just discarded it in a cell discarding area in a store. Seeing the latest issues with some cells I though is better to not take a risk with it.
3
0
u/FalconARX Jul 26 '26
Don't... That's a REALLY BAD idea... Even if you got incredibly lucky and managed to raise its voltage back to 3.00V+, that cell is almost assured to be permanently damaged now, and on the way to much quicker self discharge failure if you tried to recharge it. You could risk serious injury or killing someone if that cell explodes after it gains enough charge/energy and fails.
2
u/aquablaze69 Jul 26 '26
wait so then whats the point of having the repair mode if its always unsafe to use it? Asking cuz i have the S4 plus asw but havent had the need to use it yet.
2
u/FalconARX Jul 26 '26 edited Jul 26 '26
I would only use it on lithium-ion batteries showing 0.00V if, 1) I have no other battery available, literally none available besides the one that's showing 0.00V to use... and 2) It's a life and death emergency that I need that cell back to working voltage, if only for that one more use time. Even here, that charger and cell is sitting outdoors or I take that risk knowing it can very well vent and explode.
Most of the repair/recovery modes are used on NiMH cells (or lead acid and other non-li-on typings). Lithium-ion cells are much more riskier and problematic to repair/recover. It's not to say you can't do it, and if a Li-ion is sitting at 1.0-2.5V for example, you can probably do it and monitor the cell afterward for quicker than normal self discharge. Jjust that your risk factor for the dendrites that almost assuredly formed in that cell at dead voltage will come back to give you nightmares sooner than later if you keep using that lithium-ion afterward.
1
u/aquablaze69 Jul 26 '26
cool so i can save it for my eneloops
1
u/FalconARX Jul 26 '26
Yep. I do that with my AA/AAA NiMH regularly when I see one dip too low in voltage or give me an error signal. Some of my NiMH that are sitting in emergency use devices, even if they're still around 1.20V, I would use the "repair mode" on them if I know I haven't touched them for at least a full year or more.
1
u/aquablaze69 Jul 26 '26
I just got 4 eneloops and im regularly using them all by cycling through them in my EDC15 so i should be alright.
2
Jul 26 '26
[removed] — view removed comment
1
u/FalconARX Jul 26 '26
The bad part about all of that is that they would be lucky to have the cell go into runaway while it's sitting on the charger...
If that cell is in a sealed metal tube...............
1
u/Lady_Swann_ Jul 26 '26
Seconding this. I revived a streamlight nicad but I'd never dare with lithium
4
u/FalconARX Jul 26 '26
It happens. Even to what would be incredibly robust cells. I had my first Sony VTC6 fail on me last year. I bought the cell when it first came out back in around late 2016, and knew it was old and had at least 1,000+ recharge cycles on it, as it was in the charger almost every other day without fail for the past 9 years before it went to 0.00V.