Switching Configurations for reconfigurable battery packs: A review

Conventional Battery Energy Storage Systems (BESS) are designed with fixed cell topologies, where the electrical connection between cells remains unchanged throughout their life. Although Battery Management Systems (BMS) and conventional cell-balancing techniques are employed to monitor and maintain performance, they often fail to address key challenges such as uneven cell aging, capacity mismatch, and fault isolation that arise especially during the second life of a battery pack. These limitations can result in reduced efficiency, reduced reliability, and shortened battery life. As large-scale battery packs become increasingly common in Electric Vehicles (EVs), smart grids, robotics, and renewable energy systems, the limitations of conventional approaches primarily focused on BMS, safety circuits, and fixed balancing strategies have become more pronounced. Reconfigurable Battery Systems (RBS) are an emerging class of Energy Storage Systems (ESS) that offer flexible electrical interconnections between cells or modules. By adjusting cell configurations to series, parallel, hybrid or bypass arrangements, these systems enhance energy distribution, improve state of charge (SOC) balance, reduce degradation, and increase fault tolerance, resulting in better reliability and extended service life compared to conventional fixed-topology designs. In this paper, a comprehensive review of the switching architectures that have been employed in various RBS in literature has been conducted, focusing on the design of their switching topologies, operational principles, and associated complexities. It provides a comparative analysis of various configurations presented in the literature, examining their switch count, fault tolerance, switching complexity, and reported improvements, and offers insights into their practical implementation in adaptive ESS.