The reason a battery will discharge the cells to different voltages is that the
chemistry of each cell is difficult (expensive) to make exact. Tiny fluctuations in
the mixture, the amount of chemical, and the contact area cause measurable
differences in the capacity and discharge rates of the individual cells.
This is the reason that a
BMS is used, it charges the individual cells to a common
charged voltage.
I have an astro-flight blinky balancer for up to 6 lipo cells that does not
need the charging voltage to balance, you charge via the discharge plug,
the balancer bleeds higher charged cells into lesser charged cells during charging.
Since the GM Packs do not charge via the mains, I would not assume this to be
the same setup.
