A delayed charging enabled station for electric vehicles

Abstract

The resurgence and adoption of Electric Vehicle (EV) technology have necessitated the establishment of more Electric Vehicle Charging Stations (EVCS) to mitigate driving range anxiety among EV owners. The battery, a critical component of EVs, has garnered significant research interest, particularly concerning its lifespan management. EV batteries experience cyclic and calendar aging, which can adversely impact their performance and longevity. While cyclic aging due to vehicle operation is unavoidable, measures can be taken to mitigate calendar aging, particularly when batteries remain idle at a high State of Charge (SoC). This paper introduces a delayed charging technique designed to minimize idle periods with an SoC above 85 %, thereby reducing calendar aging. The proposed technique, implemented at EVCS, is capable of charging multiple EVs simultaneously, and leverages Internet of Things (IoT) technology to collect vehicle departure times and optimize the charging schedule. The Delayed Charging Algorithm (DCA) determines the initial SoC using the Open Circuit Voltage (OCV) method and estimates the updated SoC during charging via the Coulomb Counting (CoC) approach. By calculating the required time to reach a full charge (100 % SoC), the DCA strategically delays charging to align with departure times, effectively mitigating calendar aging. A MATLAB-based simulation was performed for a 320 V, 94.5 Ah EV battery, and the proposed methodology was validated through a hardware setup charging two 3,000 mAh Lithium-Ion (Li-ion) cells of model 18,650 simultaneously. App-based results further confirm the effectiveness of the DCA in a charging station scenario. A comparative analysis with conventional charging modes shows that the DCA reduces calendar aging by 4.7 %.