Always been told to not to let the cells drop below 3.0v, due to damaging the pack. Recently I came across an 11.1v that was over discharged and showed as 2.0, 2.0 and 2.9. It was sitting in my ammo can for a while and with my spare time today decided to see if it would recharge. Took everything to the garage, stood by with a fire extinguisher, and it seems like the battery is fine. After a while of slow charging (0.2A) it's gotten back up to 3.7v ish per cell no problem and after a few hours is still holding up fine.
So my question is, what real damage does discharging past 3.0v per cell really do? I've always read and been told that it damages the battery, but everything *seems* fine...