Energy storage systems undergo an intense application in both stationary and vehicle applications. Supercapacitors in particular present interesting proprieties due to its high power characteristics. To study and analyze its dynamic behavior it is necessary to apply test procedures, such as electrochemical impedance spectroscopy. However, the classical way in which these tests are carried out are not easily applicable to high capacitance supercapacitors, due to the high currents involved. We present a new approach to test these types of supercapacitors and develop a simple and precise dynamic model, which is experimentally validated.