Lithium ion (Li-ion) batteries are promising power sources for hybrid powertrain systems, and the thermal management of batteries has been identified as a critical issue both for safety and efficiency concerns. This work studied thermal management of a Li-ion battery module both experimentally and computationally. A battery module consisting of multiple cells was fabricated and experimentally tested in a wind tunnel facility. Systematic tests were performed under various flow velocities, charging and discharging current, and module configuration. Computationally, a high-fidelity two dimensional computational fluid dynamics (CFD) model was developed to capture the detailed dynamics of thermal management of the cells. Temperature rise of cells and pressure measurements were recorded in the experiments, and compared with CFD model simulations. Reasonable agreement was obtained, confirming the validity of the model. The validated model was then applied to study the power consumption required by the thermal management system. The results obtained in this combined experimental and numerical study are expected to be valuable for the optimized design of battery modules and the development of reduced-order models. (c) 2014 Elsevier Ltd. All rights reserved.