Method for dimensioning battery and thermal management systems for heavy-duty vehicle applications using aged battery experimental data and advanced modelling techniques

During the life of a Li-Ion battery, capacity and power capability fade. Despite this degradation, an electric vehicle battery needs to deliver designed power performance until battery end-of-life. Comprehension of battery performance degradation is required to design sufficient margin for power capability and thermal management. This paper proposes battery laboratory testing combined with advanced modelling techniques to obtain design parameters based on aged batteries. Laboratory cell aging and characterization tests are performed to parametrise models, which are used to verify electric city bus battery performance at various lifetime levels. The modelling gives an indication on the level of margin that needs to be designed for power capability and thermal management. The results obtained indicate that from performance point of view, the battery that was studied can be utilized well beyond 80% capacity point while still retaining power capability and low cell level power losses.