Patent ID: 8525519

Claim:
A method for estimating capacity of a battery, said method comprising: providing, in a processor, battery data including a previous battery state-of-charge, battery voltage, battery temperature and integrated battery current amp-hours; determining, in the processor, that battery contactors have been closed after the contactors have been opened to disconnect the battery from a load; determining, in the processor, if the battery has been at rest for a long enough period of time while the contactors were open where the battery rest time is based on battery temperature; determining, in the processor, an initial battery voltage as a battery voltage from a last time step when the battery contactors were closed prior to the contactors being open during the battery rest time; determining, in the processor, a present battery state-of-charge from the initial battery voltage and the battery temperature; and calculating, in the processor, the battery capacity based on the integrated battery current amp-hours divided by the difference between the present battery state-of-charge and the previous battery state-of-charge.