Optimizing Electric Double-Layer Capacitor Charging Efficiency through a Parallel Monitor Circuit: A Comparative Study with Lead-Acid Batteries

This research explores the challenges associated with achieving a true full charge in Electric Double-Layer Capacitors (EDLCs) during relaxation charging. The conventional method, while reaching a full charge, is considered a pseudo full charge, leading to inefficient energy utilization. The proposed solution involves a parallel monitor with a simple electronic circuit that can be electronically disconnected during relaxed charging. This innovation prevents the wasteful flow of charging current through the parallel monitor, facilitating efficient relaxation charging. Experimental results demonstrate the effectiveness of the proposed parallel monitor in contrast to conventional methods, showing promise for practical applications in cordless equipment and similar scenarios. Future work aims to enhance accuracy and adaptability to variable charging currents. This article delves into enhancing the performance of Electric Double-Layer Capacitors (EDLC), particularly in series-connected configurations. Comparisons with lead-acid batteries highlight EDLC advantages in power electronics, showcasing long cycle life and high voltage operation. Charging inefficiencies arising from series connections prompt the introduction of a minimalist parallel monitor circuit. This circuit, utilizing only one MOSFET and two resistors, ensures uniform voltage distribution during charging. Additionally, it incorporates an electronic disconnection feature for relaxed charging, improving charging efficiency by over 25%. Experimental validation with a series-connected EDLC charging circuit demonstrates the effectiveness and practical utility of the proposed parallel monitor.