Charge state algorithm for lead acid battery in hybrid electric vehicle

摘要

A method and apparatus for determining the state of charge of a lead-acid battery. The present invention includes steps to determine a current-based state of charge while accounting for such factors as current, temperature, charge efficiency, parasitic losses and self-discharge. The present invention is capable of measuring and/or calculating the open circuit voltage during and after operation to determine a voltage-based state of charge while compensating the open circuit voltage for its transient behavior and accounting for the voltage shift caused by charge events. The correlation of the open circuit voltage to the state of charge is dependent on the battery's mode of operation. The present invention is adaptive to battery aging by updating the battery resistance, correcting coulomb errors, and accounting for capacity degradation while in operation.