Patent ID: 8115453

Claim:
A system for managing energy stored in a plurality of series connected energy storage units, the system comprising: a plurality of energy storage unit controllers, each controller being associated with one of the plurality of energy storage units; a current pump to transfer energy between two of the energy storage units independent of the difference in voltage between them, the current pump being controlled by at least one of the energy storage unit controllers; a measurement circuit having a measuring function indicative of a state of charge of at least one of the energy storage units; a central controller in electrical communication with the energy storage unit controllers, the central controller being coupled to the measurement circuit for receiving the indications of the state of charge and having a charge movement function whereby energy storage unit imbalance can be anticipated before it occurs; and an electrical interface between the energy storage unit controllers for providing bi-directional communication to control the energy storage unit controllers to transfer energy between energy storage units.