just a few months ago, one of my xtar 18700, once charged and stored, read 0.0 volts. The charger indicated it was gone for good, as well, so I I taped up the terminals and tossed it into my recycle bin. Fast forward to yesterday, when I was dumping a couple used AA copper tops I found at work, I picked the old 18700 up again, and shoved it into one of my solarforce torches- and it lit right up! Pulled the battery to check its voltage, and it read 3.4 volts - nothing I would have expected. I put it back into the charger, and it took well over ten hours (!!!) to charge it to 4.2 volts.
I’m going to keep an eye on this zombie cell, for sure.
I fully charged the cell in spring, then discharged it a bit, using it in one of my P60s for a few minutes. It still read 4.1V then, and I put it away. It then sat for about eight weeks, until I discovered it has gone to nought.
My DMM (Gossen Metrawatt) read 0.0V. The WP2 (bought Christmas 2011) wouldn’t charge it, and the unbranded solarforce charger (came with a package deal in early 2011) didn’t charge it either, so I discarded it into my battery wastebin where I collect all my old cells.
Merely out of curiousity, I fished it out again, to find it back alive. Do protection circuits reset themselves?