The idea is to shunt some current around a LiFePO cell once it is charged to 3.3V. The shunt starts to let current flow at 3.3V and increases up to 75mA at 3.65V when the cell should stop charging. This will also serve to release over charge which can happen as the battery cools off.
LiFePO info:
http://www.powerstream.com/LLLF.htm
TLVH431 Equivalent circuit includes: op-amp, 1.24V ref, and NPN.
Balancing will cause all the cells to be full charged at about the same time. During discharge the smallest capacity cell will trip the disconnect since its voltage will drop first, and will also determine the overall battery capacity.
Self-discharge is almost non-existent in LiFePO4, but this will have 80uA
