A Li-ion Battery String Protection System

For lithium-breed batteries, the fragility and sensitivity upon terminal voltage, high-temperature environment or too high current are all harmful. Consequently, versatile protecting circuits are requisites for lithium batteries. Furthermore, for high voltage applications, series-connected battery string is a normally adopted as the power source. In a lithium-battery string, every single battery unit should be protected as fore-mentioned. This paper is aimed to carry out a protection system for ten series-connected lithium batteries. This power system is kernelled with a Microchip-based dsPIC controller. Together with associated detecting circuit, the controller can perform protection functions for preventing hazards such as over-voltage, under-voltage, over-temperature and over-current.