Abstract: A portable hand-carrying auto-polarity battery booster apparatus includes a power storage device which is capable of providing power to an electrical system such as a battery. For example, the portable apparatus can be used to jump start a vehicle with a dead battery. The apparatus is compact in size which encloses the power storage device, the at least four connecting cables, and many other electrical circuits in a compact housing. The portable apparatus also includes an auto-polarity switch in the housing which ensures a proper polarity connection between the power storage device of the apparatus and the electrical system, as well as an ON/OFF switch located between the battery and the auto-polarity switch.