18650 TF Flame failed during charging

Fortunately, failed dead, rather than failed by venting with flame...

About a week ago, I put one of my 18650 TF Flames in my TR-001 (charges to 4.18, but trickles). Normally I watch them like a hawk, but I someone came by, so I didn't check it for 16 hours or so, which at the rate the tr-001 charges (it takes a very long time to get the last bit of charge in), isn't that long. Checked it when I got back, light was green. Pulled it out, put it in a flashlight... nothing. Checked voltage, nothing. In the last few days, I tried to reset the protection board, nothing. Today I scraped off a bit of the plastic wrap, measured from the side to the positive end... 0.5V.

The cell was probably 50% charged when I put it on the charger, and had been working perfectly. Cell was probably a month or two old, with 10-20 cycles on it, never over-discharged.

I'm not sure if it got overcharged (I tested another pair of cells in the charger, and there was no sign of overcharging), or if it just decided randomly to die. Or maybe the protection board failed and drained the cell. Since it's so badly over-discharged, I'm not going to try re-charging it to test which it was.

I'll be watching them even closer when charging now...

--Bushytails

That's odd. Where did you get the battery?