Patent ID: 8933666
Filing Date: 2015-01-13
Classification: H02J

Abstract:
1. A method of equalizing charge states of individual cells in a battery, the method comprising: measuring a previous cell voltage for each cell; measuring a previous shunt current for each cell; calculating, based on the previous cell voltage and the previous shunt current, an adjusted cell voltage for each cell; determining a lowest adjusted cell voltage from among the calculated adjusted cell voltages; and calculating a new shunt current for each cell, wherein the calculating the new shunt current for each cell comprises: setting the new shunt current for the cell having the lowest adjusted cell voltage to zero; and calculating a new shunt current for each of the remaining cells according to the following equation: ISNn is the new shunt current, ΔCTp is the difference between the nominal battery capacity at charge termination and the nominal battery capacity at discharge termination at temperature Tp, VNpi is the adjusted cell voltage, VLpi is the lowest adjusted cell voltage from among the adjusted cell voltages of each of the N cells, B is the target time to substantially fully equalize the charge states, VH is the cell charge voltage limit, and VL is the cell discharge voltage limit.