in the energy storage unit 12 reaches or exceeds a minimum threshold level more specifically the scm controller 20 may prevent any energy generated by the energy recharge unit 10 and any energy in energy storage unit 12 from being delivered to the load 16 until such time as the energy storage unit 12 has reached a minimum threshold of energy storage or a minimum charge level as stated above in fig1 the energy storage unit 12 uses the ultracapacitors 26 which can deliver extreme cycle counts 100 000 or more thus supporting decades of daily or even more frequent cycles these ultracapacitors 26 have limited voltage ratings typically 2 3 to 2 7 v each so they are used in series combinations in most storage applications in series combinations a charge imbalance is reflected as a voltage imbalance and it is imperative to make sure the highest voltage in the series string stays below the operating limit furthermore life extension can be obtained if an even lower voltage limit is enforced similar limitations based on voltage apply to batteries which can be used in place of ultracapacitors 26 with only minor circuit modifications in the embodiment of fig1 the energy storage unit 12 is coupled to an equalizer 22 the equalizer 22 can guarantee that each of the ultracapacitors 26 has a corresponding voltage that is a correct fraction of the total string voltage thus if there are 5 ultracapacitors 26 in series and the total voltage is 10 0 v then each individual.