Dewster..... that is an excellent question...... In my opinion, since the cells are wired in series and all the recharging energy comes through the single series circuit, there is no way for additional current or voltage to target any unbalanced cells. The purpose of the balancer is to monitor the condition of all cells and to adjust charging and discharging within the constraints of the weakest cell. Otherwise the weakest cell would become damaged and make the entire pack useless.
However a discharge cycle might help to reduce all cell levels closer to a common level such that a subsequent recharge cycle will result in better full charge balancing.
I agree with your narration and description Peter but I believe that Individual cell balancing is not only possible but takes place every time you charge a battery. Let me explain:
As the battery charges, every cell receives the same amount of energy (watts) BUT when any of your cells reaches a tension of 4.2 volts (max 4.210 v.), the charger will not allow this value to be exceeded for that one cell (I suspect through the cell balancer connection). While this is happening, the other cells' voltage keeps going up until they also reach 4.2 volts or very close. Only when all the cells are at 4.2 volts will the charger release the battery with the 100% charged ticket. I my opinion, when all the other cells are catching up to level 4.2 volts, they are actually balancing their charges in relation to the fully charged cell.
In other words, you start with the same tension in all the cells after every charge. As there is no control as to how fast every cell will discharge their energy, you often notice a gap after the flight when you connect to the charger, and the cycle starts again. When a cell is no longer capable of catching up the 4.2 level, even after several minutes of ''individual'' charging, then the pack becomes unsafe for flight. May be OK for cars or other earth attached vehicules, but IMHO the battery should be discarded.
