Patent ID: 7630181

Claim:
An ultracapacitor energy storage cell pack, comprising: an ultracapacitor assembly including a plurality of parallel ultracapacitors and balancing resistors in series, each balancing resistor in parallel with each ultracapacitor to automatically discharge each ultracapacitor over time, thereby balancing the ultracapacitors of the ultracapacitor assembly; an enclosure to enclose and protect the ultracapacitor assembly; one or more temperature sensors to monitor temperature of the ultracapacitor assembly; a pack voltage sensor to monitor voltage of the ultracapacitor assembly; a ground fault sensor to monitor for a ground fault condition of the ultracapacitor assembly; a cooling system to cool the ultracapacitor assembly; an on/off relay coupled to the ultracapacitor assembly and a control input, the on/off relay activated during normal operation of the ultracapacitor assembly and deactivated by the control input to terminate normal operation; and a pre-charge resistor and a pre-charge relay coupled to the ultracapacitor assembly and the control input, the pre-charge relay activated by the control input to cause the pre-charge resistor to limit pack incoming current until the ultracapacitor assembly reaches a minimum voltage.