Designing small batteries and adaptive charging strategies for operation on rough terrain

Abstract

The global trajectory is swiftly progressing towards the adoption of electric vehicles (EVs). Given that batteries constitute a pivotal component within the domain of EV technology, their performance and life have become of utmost importance. Battery life is affected by multiple internal and external factors. This paper addresses real-time challenges associated with using battery packs in dynamic on-road conditions characterized by variable discharge rates, temperatures, depth of discharge, storage conditions, and rough terrains. The study involves designing 2.8kWh battery packs and using them to power e-rickshaws in on-road conditions in places like India. The study shows how minor issues, which are often overlooked during the initial pack design phase, can impact the long-term operational performance of the batteries.In real-world scenarios, users lack control over the discharge of a battery. However, the charging process can be effectively controlled. In this paper, we propose an adaptive slow-charging strategy to prolong the life of the battery pack. The suggested charging algorithm regulates the charging current based on parameters such as battery temperature, state of health, and terminal voltage. To assess the impact of this algorithm, we conducted tests on 2.8kWh battery packs used in e-rickshaws for over two years under real-world driving conditions. The effectiveness of the proposed algorithm is demonstrated by comparing the battery degradation with the standard constant current constant voltage charging. The study also introduces a novel balancing technique involving temporary suspension of balancing and charging currents during voltage measurements, mitigating errors linked to ohmic drops. Additionally, the research examines the degradation caused by parking vehicles for extended periods.