Numerical study of an air-cooled battery pack: Effects of time-averaging heat generation in a case study

In the quest for cleaner energy sources in the automotive industry, lithium-ion batteries are increasingly favored as an alternative to fossil fuels. However, their performance, lifespan, and safety are highly influenced by operating temperatures. Consequently, extensive research is underway to develop more efficient battery thermal management systems (BTMS), taking into account the predicted average output of battery packs.

This study conducts a numerical analysis of the performance of an air-cooled battery pack used in a formula-style racing car. Unlike traditional approaches that use a constant heat source, the simulation here employs the actual electric current consumed by the vehicle's motor, estimated through a vehicle dynamics simulation on the race track. The battery cells are represented using an equivalent circuit model (ECM), consisting of three parallel resistance-capacitor (RC) elements, evaluated at three different temperatures.

We compare two scenarios: one using a time-averaged constant current, and the other applying a variable, transient current derived from vehicle dynamics simulations. Our findings reveal that the scenario with transient current results in a 6 °C (12.9%) increase in maximum cell temperature. This highlights the significance of incorporating realistic drive cycles in BTMS design and highlights the importance of dynamic current profiles in accurately predicting battery performance and temperature management.