I had a Sanyo UR14500P unprotected cell sitting inside a UTorch UT01 for a couple of weeks. Probably due to the faulty switch, the light drained the cell down to 0.6V. Ugh. Would you toss this cell or try to revive it? Not sure it’s safe to charge at this point…
Tossing it would be the safest option.
Reviving it would result in a reduced capacity, overall stability and lifespan as well as drastically increasing the risk of catastrophic failure.
If it’s been that low for that long, charging could be dangerous. Dispose of it properly.
I fly the Phantom 4, which uses large battery packs. When a battery pack starts going bad I drown it in a bowl of salt water, which completely discharges the battery pack and makes it safe.
I would recycle it. It is not worth the risk and the battery probably would be much weaker anyway. These batteries do not cost that much,better to spend a few dollars and have peace of mind.
Just yesterday I noticed my Ultratac K18 SS Keychain light was not working. I checked the battery which was an Efest IMR 10440.As soon as I took it out I knew something was not right. The wrapper on the positive and negative ends was peeled back a bit! Not sure what caused that. The voltage was 0.536V!! I am lucky that Staples is 1 mile away. That is where I take my batteries to be recycled.No excuse to throw them away.