Patent ID: 7345455
Filing Date: 2008-03-18
Classification: H02J

Abstract:
1. A backup-battery system, comprising: a first battery pack having a first effective energy capacity and a first maximum energy capacity; a second battery pack having a second effective energy capacity and a second maximum energy capacity; a charging circuit electrically connected to the first and second battery packs; a control device including a power sensor and a lower threshold and an upper threshold; wherein said power sensor is adapted to detect when the first energy capacity falls below the lower threshold and the control device is adapted to direct the charging circuit to charge the first battery pack to the first maximum energy capacity; wherein the power sensor is further adapted to detect when the first energy capacity and the second energy capacity fall below the upper threshold and the control device is further adapted to direct the charging circuit to charge the first battery pack to the first maximum energy capacity; a third battery pack having a third effective energy capacity and a third maximum energy capacity; wherein the power sensor is further adapted to detect when any two of the energy capacities have fallen below the upper threshold and the control device is further adapted to direct the charging circuit to charge the first battery pack to the first maximum energy capacity; and a discharge circuit electrically connected to the first, second, and third battery packs and the control device is further adapted to direct the discharge circuit to discharge the first battery pack to the lower threshold before directing the charging circuit to charge the first battery pack to the first maximum energy capacity.