Patent ID: 7443140

Claim:
A method for operating a battery to terminate discharge of said battery to avoid damage to said battery and substantially maximize use of chemical capacity of said battery; the method comprising the steps of: (a) determining a first depth of discharge of said battery while said battery is in a relaxed state before commencement of a first battery operation; (b) determining current flow from said battery during said first battery operation; (c) determining a second depth of discharge of said battery while said battery is in a relaxed state after completion of said first battery operation; (d) determining a battery voltage across said battery; (e) employing said first depth of discharge, said second depth of discharge and said current flow for determining a maximum chemical capacity of said battery after completion of said first battery operation; (f) during a next battery operation following said first battery operation, integrating current flow from said battery with respect to time over a time interval to determine an integrated charge value at an end-of-interval-time substantially when said interval ends; (g) employing said maximum chemical capacity, said integrated charge value and said first depth of discharge to determine an extant depth of discharge at said end-of-interval-time; (h) if said extant depth of discharge is neither within a first predetermined range of a predefined maximum depth of discharge nor said battery voltage is within a second predetermined range of a predefined minimum voltage, carrying out steps (f) through (g); (i) if said extant depth of discharge is within a first predetermined range of a predefined maximum depth of discharge or if said battery voltage is within a second predetermined range of a predefined minimum voltage, terminating said next battery operation.