Lithium-ion Traction Battery Design for FSAE Racing Car

This thesis work discusses the detailed design of the Traction Battery of the 2018 FSAE season car, a project on which I have been working as Technical Director of the PoliTO racing team in the academic year 2017-2018. The starting point for the car development was the analysis of the weaknesses of the previous car, with a focus on the improvement of the vehicle handling, aerodynamic, control as well as on weight reduction. The Traction Battery resulted to have a huge impact on the vehicle weight and packaging. A new design has been crucial to lower the center of gravity and allow the integration of a diffuser which increased the vehicle downforce. Power and Energy targets were established using data from the previous season races, and the safety requirements were updated according to the current FSAE regulations. Together, these factors drove most of the technical choices. The Traction Battery used a new cell chemistry, which resulted in an overall increased specific energy while keeping the same nominal energy and specific power. Cell selection was done based on literature review to understand cell behavior and characteristics at different operating conditions. Experimental tests were performed to validate an equivalent model for electric and thermal simulations, conducted to deliver the best parallel and series configuration along with an optimized cooling system. Cells connection was found to play a fundamental role in the design choices. A new cell bonding technology was adopted, which provided the best performance and reliability outcomes, simplifying the manufacturing and assembly processes. The achieved results show that the designed Traction Battery could withstand the maximum power request during all dynamic events and store enough energy to complete the endurance event with remarkable results in efficiency.