Murata's supercapacitor(EDLC) has two individual cells connected electrically in series. Therefore there is a possibility that each voltage that is impressed to each capacitor may be unbalanced due to variation of each capacitance or insulated resistance. When such unbalance occurs during using supercapacitor, impressed voltage to one cell will be large. If the voltage exceeds the limited value, it causes large electrical degradation. And difference of impressed voltage may also cause difference of life time between each cells, as a result it may reduce life time of supercapacitor.
For balance of such voltages, supercapacitors need to have balance control of each applied voltage. There are two methods, one is passive balance control and the other is active balance control. For details, please refer to "Recommended balance condition" or contact your local Murata representative.