I recently bought a couple of samsung 18650 INR 30q… a few days after they arrived I had a urgent need of charging my girlfriend’s mobile phone since she was in a hurry to go to work and realized the battery was nearly gone, so I grabbed a crappy chinese powerbank that I had laying on my desktop and the first charged battery I had at hand, the samsung, (ironically, a friend of mine bought the power bank and I said him “I wouldn’t trust that thing, give it to me and i’ll check if it seems ok or not”), and gave everything to my girlfriend saying “just remember to remove the cable when the battery is half charged!” (i was worried about the power bank lacking a low voltage cutoff or having it too low).
Well, after a couple of days she gave me back everything… and I found the battery was at 0 Volt! I mean literally 0.00!!! That was what my multimeter was showing! I couldn’t believe my eyes by the way she kept her phone connected for just a few tens of minutes and then disconnected the cable (but didn’t remove the battery), so that device is clearly defective (i wanted to check its parasitic drain but I don’t have it with me at the moment, I’ll measure in the next days).
I know it’s not very wise, but since the cell was brand new (I think I have charged it just once) I couldn’t stand the idea of tossing I right away… so I tried putting a few tens of mA to it and see what happened. The voltage was slowly rising… to put it short, i went on this way, stopping every now and then to check if it was holding the charge and everything seemed ok. When I reached 3.0 volt I moved it to my charger set to 300 mA… at 3.6 volt it was still holding the charge for several hours! So i put it back in and completed the charging at 4.2. Tried discharging for a few minutes at different currents and everything was ok… so I filled it again and tried a discharge test at 250 mA…
…that showed 3019 mAh discharged!!! that’s even a few mAh more than its twin cell, that stopped at exactly 3000 mAh!!!
Is such a resurrection even possible?? Honestly I’m considering just putting it back together with my other cells and using it like if nothing happened… I have marked it with a red cross and I’m testing it in a flashlight now, but I have not seen a single oddity or anything suspicious, even the Astrolux S1 works just fine drawing over 5A!
I didn’t know that, I thought it was more like “it’s better not to charge it again because it might short/explode if you do”, not “it might complete the charge normally and work flawlessly, but then suddenly short/explode later in the future use”.
Also the fact the capacity is 100% the rated one doesn’t exclude that there may be some internal damage to the chemistry? (I’m not good a chemistry, but if the electrodes or the electrolite have undergone a significant change then I would expect that also the cell behaviour would be affected, such as the capacity for example).
P.S.
I just realized that NCM stands for Nichel Cobalt Manganese, so it’s basically another name for INR… so there is indeed something about INR too in the sticky thread about overdischarge, even though just in this image:
The difference in the voltages are almost negligible, but maybe the fact that nichel based chemistries are separated from the others might indicate a different behaviour when overdischarged… but of course that’s pure speculation.
I’ve never read the NASA reports myself, but I have heard that they determined cells would either vent or explode (not sure which) after repeated over discharge cycles. What I heard was after 50 cycles. What every you do. Don’t go by my recollection of what I heard. Check into it yourself.
If what I heard is right, it seems your cell may be safe. I wouldn’t use it if it gets hot when charging or if you test internal resistance and it is high. Probably shouldn’t use it in series with other cells no matter what.
If you're going to quote someone, at least do it properly.
I was very clear that what I said I heard should be verified. I'm not going to search for "evidence" on your behalf. I did a quick google and found many reports. All, indicated that the OP's cell may or may not be safe to continue to use. For example, here is a sentence from Lithium -Ion Batteries Hazard and Use Assessment - Final Report, by Exponent Failure Analysis Associates, on behalf of the Fire Protection Research Foundation (Bold and Underlines added by me):
"Simply over-discharging a lithium-ion cell to 0 V will not cause a thermal runaway reaction. However, such over-discharge can cause internal damage to electrodes and current collectors (i.e., dissolution of copper) (Figure 33), can lead to lithium plating if the cell is recharged (particularly, if the cell is repeatedly over-discharged), and can ultimately lead to thermal runaway."
To say something may be is also to say it may not be. Additionally, I was very clear that I what I recalled hearing could be incorrect. It was the best I could recall and said it should not be relied upon and should be verified.
I appreciate you call to only make safe statements. I certainly don’t want to mislead anyone into dangerous activities unaware. I don’t believe my post taken as a whole does that.
So now let me ask you to Please either fully quote (partial quoting is mis-quoting in my opinion) or make it clear you are partially quoting. Also, don’t twist the meaning of what a BLF member posts. I will not reply to any more of your trollish statements on this matter.
by the way she kept her phone connected for just a few tens of minutes and then disconnected the cable (but didn’t remove the battery), so that device is clearly defective (i wanted to check its parasitic drain but I don’t have it with me at the moment, I’ll measure in the next days).
