BigBobby:
You asked about 10 cell batteries, however, and once you start using 4 or more cells voltage dividers are less practical.
Battery stack cell fuel gauge ICs seem to be made of unobtanium.
I'm currently trying with relays and "flying caps".
Upto ~120volt stack, with ZERO current drain on each cell.
Despite the relays, total current drain of the setup is very low.
The low-power relays are only activated for ~30mSec.
Chattering seems to be the only problem.
Bluetooth/smartphone cell graphing is the next challenge.
Leo..