Patent ID: 7554295

Claim:
A battery control module for use with a battery, comprising: a voltage measuring module that measures battery voltage; a current measuring module that measures battery current; and a state of charge (SOC) module that communicates with said current and voltage measuring modules, wherein said SOC module estimates an open circuit voltage based on said battery current and said battery voltage; and wherein said SOC module estimates said open circuit voltage, when said battery is charging, based on an equation V 0 =( V+vDsch Event−( I+iDsch Eventheld)* R 0 )/2, where R 0 is an internal impedance of the battery, V is the battery voltage, I is the battery current, vDschEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is discharging, and iDschEventHeld is the battery current during the previous determination of the open circuit voltage, and wherein said SOC module estimates a SOC based on said open circuit voltage.