Battery pack states, properties, and characterization techniques beyond cell level

Battery packs, defined as interconnections of individual cells, are central to modern energy systems, yet their electrical and electrochemical behavior remains insufficiently understood. This review consolidates foundational principles, outlines challenges, and addresses fragmented knowledge that hinders further development at the pack level. A key challenge is the lack of harmonized and uniquely defined states, such as the state of charge and the state of health. To address this, we propose revised definitions and introduce state descriptors for more consistent and comparable pack-level analysis. We critically evaluate existing characterization methods, originally developed for single cells, and highlight their potential and limitations at the pack level. Many of these methods require further adaptation, and only their combination with harmonized state descriptors enables reliable and meaningful results. This work goes beyond identifying challenges by closing gaps in state descriptions, providing a foundation for future research, fostering reliable diagnostics, and supporting innovation in energy storage technologies.     «

Battery packs, defined as interconnections of individual cells, are central to modern energy systems, yet their electrical and electrochemical behavior remains insufficiently understood. This review consolidates foundational principles, outlines challenges, and addresses fragmented knowledge that hinders further development at the pack level. A key challenge is the lack of harmonized and uniquely defined states, such as the state of charge and the state of health. To address this, we propose...     »