This manual does not contain complex theoretical calculations, formulas and graphs that describe the variety of electrochemical and physical processes occurring in a battery. Only acid starter batteries are considered. A minimum number of concepts and information is given, sufficient to understand the basic processes, allowing the car enthusiast to independently, without much effort and time, organize rational care for the battery and extend its trouble-free operation. The manual is intended for car enthusiasts who, for the most part, do not are specialists in the field of chemical current sources, however, it is assumed that the reader has an understanding of the structure of a modern rechargeable battery.