Abstract: An ultracapacitor energy storage cell pack includes an ultracapacitor assembly including a plurality of parallel ultracapacitors and balancing resistors in series; an enclosure for the ultracapacitor assembly; a controller; one or more temperature sensors; a pack voltage sensor; a GFI sensor; one or more cooling fans carried by the enclosure; an on/off relay coupled to the ultracapacitor assembly and the controller, the on/off relay activated by the controller during normal operation of the ultracapacitor assembly and deactivated by the controller when the GFI sensor detects a ground fault interrupt condition, the one or more temperature sensors detect an over-temperature condition, or the pack voltage sensor detects an over-voltage condition; and a pre-charge resistor and a pre-charge relay coupled to the ultracapacitor assembly and the controller, and activated by the controller to cause the pre-charge resistor to limit pack charge current until the ultracapacitor assembly reaches a minimum voltage.

Abstract: An ultracapacitor energy storage cell pack includes an ultracapacitor assembly having a plurality of series connected ultracapacitors and balancing resistors, each balancing resistor connected in parallel with each ultracapacitor to automatically balance each ultracapacitor over time, thereby automatically over time discharging the ultracapacitors of the ultracapacitor assembly; an enclosure to enclose and protect the ultracapacitor assembly; a controller for the ultracapacitor assembly; and one or more temperature sensors to monitor temperature of the ultracapacitor assembly and coupled to the controller.