Using battery in mobile system

Human being has been familiar with mobile system such as smart phone, tablet PC and smart robot-cleaner. These systems differ from fixed type system. Fixed system´s power is normally supplied from socket outlet. However, battery supplies power to mobile system; battery have become important energy source in system that has mobility. Therefore, researchers have interested in the mobile system to have long life-span. They have studied on battery management and algorithm of battery state. Further, researchers have tried to use renewable energy to replace the energy source or to use as a back-up power. This paper study on expanding mobile system life-span by considering the discharge and charge characteristic of battery.