Intelligent charging and control of portable battery packs

Abstract: This report describes thesis work performed at SAAB Aerotech in Link oping, Sweden. The task was to nd a way to have portable electronics' battery packs supervise their own charg- ing i.e. designing a charger that would t inside the battery pack itself. The work was started by identifying the demands that SAAB Aerotech and their customer have on portable bat- tery packs. A survey was done, forming the basis of a design specication that species what an implementation should aim at fullling. The resulting design specication closely matches what is known as a smart battery, but with dierent character- istics especially when it comes to driving high power loads and coping with rough conditions. Therefore, this report describes one possible way to implement \Smart Battery" functionality in a battery pack while at the same time adressing the special de- mands of the company. A Smart Battery is capable of measuring and logging data, and uses this data to predict performance. A communication inteface can then convey this information to host equipment and chargers. A background to what smart batteries do dierently than dumb batteries is given in the beginning of the report. Following chapters discuss battery technology and smart batteries in more detail. The main portion of the report is the description of the design and implementation of a prototype smart battery pack. This section describes choice of hardware, circuit board design and coding in C. The report is concluded with results from the design and implementation. Recommendations on further work are also presented.