This book provides a detailed examination of battery management systems (BMS) for large lithium-ion battery applications, including electric vehicles, renewable energy storage, and industrial systems. It explores the principles of battery monitoring, state-of-charge estimation, thermal management, and safety protocols. The text also covers design strategies, control algorithms, and system integration, emphasizing efficiency, longevity, and operational safety. By addressing challenges such as cell balancing, degradation analysis, and fault detection, the book equips readers with knowledge to optimize battery performance and reliability. It integrates theoretical foundations with practical applications, making it suitable for students, engineers, and professionals working in energy storage and battery technology. The book highlights the role of innovation and technological advancement in supporting sustainable and high-performance energy systems.