Peukert's Law for Supercapacitors With Constant Power Loads: Applicability and Application

This paper examines the applicability of Peukert's law to supercapacitors with constant power loads and the application of this relationship in predicting the supercapacitor discharge time during a constant power discharge process. Originally developed for lead-acid batteries, Peukert's law states that the delivered charge increases when the discharge current decreases. This paper shows that Peukert's law applies to supercapacitors when the discharge power is above a certain threshold and does not apply anymore when the discharge power is sufficiently low. This pattern is due to the combined effects of three aspects of the supercapacitor physics: porous electrode structure, charge redistribution, and self-discharge. Based on the applicability study, this paper demonstrates the effectiveness of Peukert's law in predicting the supercapacitor discharge time during a constant power discharge process by conducting extensive experiments using three supercapacitor samples with different rated capacitances from different manufacturers at various voltages.