Nickel-hydrogen battery cells provide one of the longest-lived and most reliable rechargeable battery systems ever developed. The Aerospace Corporation was instrumental in the research, development, and testing of such batteries. Primarily developed for use in satellite and space power systems, their exceptionally long life was well worth the high cost associated with the technology, and they rapidly replaced most of the nickel-cadmium batteries used in earlier satellites. This book provides the reader with an in-depth view of nickel-hydrogen cell technology: how it was developed, how and why it works, how to implement it and realize its ultimate capability, and what can go wrong if it is not properly managed. The book is organized into three separate parts that provide a balanced picture of the development of nickel-hydrogen cell technology, the fundamental principles of operation for the key components in the cell, and the key concepts involved in the use of nickel-hydrogen technology in satellite power systems. Part I introduces the subject, Part II explores the fundamental principles involved, and Part III discusses the application and practice of using state-of-the-art nickel-hydrogen cells in battery power systems.