Patent ID: 6844704

Claim:
Am active voltage limiting and failure detection system for an energy storage cell of a multiple energy storage cell pack, the energy storage cell having a cell voltage Vcell, the system comprising: a first electrical circuit connected to and powered by the energy storage cell, the first electrical circuit drawing a significant amount of power from the energy storage cell when a cell voltage Vcell reaches a maximum voltage Vmax to reduce the cell voltage Vcell, to stop drawing the significant amount of power to reduce the cell voltage Vcell when the cell voltage Vcell reaches a minimum voltage Vmin, and to draw no power when the cell voltage Vcell reaches a shutdown voltage Vshutdown; and a second electrical circuit connected to the energy storage cell and indicating a cell active condition when the cell voltage Vcell is above a threshold active voltage Vactive, and to indicate a cell inactive condition when the cell voltage Vcell drops below the threshold active voltage Vactive.