This book provides a brief introduction to applicable terms and technologies in hydrogen energetics, and allows readers to expand their view in historical development stages of various components in this field. Present day technologies develop at a pace where latest news can be found directly at the producer, or doing extensive research over range of publications. Maybe readers have thought about extending usage time of their portable devices, and there is not only theoretical possibility to do this with hydrogen technology, but practical fuel cell chargers which can be used, and now – understood via this book.