When a number of supercapacitor modules connected in series they lead to unequal voltage distributions during several cycles of charge-discharge and overvoltage may appear on supercapacitors. Therefore it is necessary to prevent this unbalance and hence to prevent individual supercapacitors from exceeding its rated voltage. This paper studies the problem of unequal voltages sharing in a series connection of supercapacitors using balancing resistor to forcing the equal sharing of their voltages. Passive resistor was tested for slow and fast balancing by carrying out simulation and experimentation. Accordingly, the results were evaluated in terms of voltage sharing, balancing period and power dissipation.