Managing the battery pack for hybrid and electric vehicles is a challenging problem. The objective of decreasing fossil fuel consumption while increasing drivability is in conflict with the objective of prolonging the life of a vehicle battery pack. If the full energy content of the battery pack is used, then fewer batteries can be used and more gains in fuel economy are possible. However, the life of a rechargeable battery can be significantly shortened when the battery is fully discharged or overcharged. In addition, overcharging (especially in the case of the lithium ion battery) can lead to catastrophic failure in the form of thermal runaway. Therefore, combining the objectives of improving fuel economy and drivability with that of maximizing battery life shows the necessity for accurate state of charge management of the battery. Furthermore, as batteries age, they become less able to store and supply energy. Consequently, some form of battery management system must estimate the state of health of the battery pack so that the vehicle control strategies can be adjusted. A battery management system (BMS) is a general term that refers to the system that directly controls and maintains a battery or a battery pack. Specific functionalities are thermal control, cell balancing, state of charge (SoC) estimation, state-of-health estimation, and pack prognostics.
The Energy Storage Systems Lab at UT Dallas, in the Department of Systems Engineering, is home to faculty and students (graduate and undergraduate) who are working on problems related to energy storage for vehicle applications, as well as stationary applications for larger, complex systems. The facilities were developed to provide opportunity for hands-on research in battery cycling (charge and discharge cycles) for data collection used in battery/pack modeling and estimation for electric and hybrid vehicle applications. Individual batteries are instrumented, as well as groups of batteries into larger packs.