This book provides a detailed description of battery modeling, which covers topics of OCV dependency and RC-based linear models of batteries, as well as thermal modeling. Methods of estimating parameters of such models are provided both in frequency and time domain experiments. Giving a strong mathematical background for implementing the methods mentioned, as well as providing detailed examples useful for reinforcing the material with the students. Battery gauging sections show how battery models can be used in order to provide accurate battery gauging. Gauging methods involving voltage correlation and coulomb counting are covered, with a description of how capacity can be updated with battery aging. Statistical methods are provided that allow you to deal with noise measurement and provide accurate estimates. The book gives a description of traditional CC/CV charging methods as well as provides an optimization that allows finding compromise between charging time and energy loss. The evaluation and benchmarking of the battery management system is described with detailed examples. The book will be a useful guide for battery engineers and students studying battery modeling and gauging systems.