It is widely known that Lithium-polymer cells are permanently damaged if their voltage drops below a certain threshold, around 3.0 volts, but I couldn't find much on the exact conditions and factors that regulate how this damage takes place (Which, I suppose, is related to the fact that few other applications dealing with lipos involve remotely as much recklessness as we subject them to).
The first of them is the contribution of voltage drop from internal resistance when the pack is under load. i.e. does the damage begin whenever a current (e.g. from a punchout) dips the pack's voltage, as observed from its terminals, below 3.0V/cell, or does the pack's "actual", resting voltage with no current drawn have to get that low?
Second, how fast does the performance of the battery degrade, and at what point does it stop? If voltage gets dropped (via IR) by a high current and it leads to damage, does it stop accumulating immediately as the current is removed and the voltage comes back up? What happens when a battery is discharged so that its resting voltage is below 3.0V, but is quickly charged back up or its voltage naturally bounces back somewhat?
Third, how significant is the time spent by the battery below the threshold versus the very fact of dipping down, i.e. what difference does it make if one rushes to charge an overdrained pack back to an acceptable voltage right after ripping it out of the aircraft (probably from another pack), versus doing it after getting home?
And finally, how does previously sustained damage from over-discharge contribute to further damage?
Note: Some context regarding how this kind of damage relates to degradation from the other abuse that we subject our cells to would be very much appreciated, although the main focus is still the undervoltage-related damage itself.