Effects of fan speed and activation pattern on thermal performance of a forced air-cooled lithium-ion battery module: An experimental and statistical study

This study experimentally investigates the thermal performance of a forced air-cooling system for a lithium-ion battery module consisting of nine cylindrical 18650 cells arranged in a 3×3 configuration. A six-fan array was employed in which each fan can be independently activated, enabling systematic variation of both airflow intensity and spatial airflow distribution. A total of 72 experimental runs were conducted by combining two discharge rates (2C and 3C), three fan rotational speeds (1000, 3000, and 5000 rpm), and twelve fan activation patterns derived from an L12 experimental design. The thermal performance of each configuration was evaluated in terms of maximum cell temperature (T max ) and inter-cell temperature difference (ΔT). Analysis of Variance (ANOVA) was applied separately for each discharge rate and for the combined dataset to quantify the relative contributions of the governing parameters to each thermal response. When all parameters were considered simultaneously, discharge rate was identified as the most influential factor for both responses, contributing 52.10% to the variation in T max and 32.60% to the variation in ΔT. Fan rotational speed was the dominant cooling parameter controlling T max , accounting for approximately 87% and 86% of the total variance under 2C and 3C conditions, respectively. In contrast, the fan activation pattern emerged as the primary cooling parameter influencing ΔT under the 2C condition (63.44%), while fan speed became more influential at 3C (35.89%). These findings demonstrate that T max and ΔT respond differently to the same cooling parameters, and that an effective battery thermal management strategy must address airflow intensity and airflow distribution simultaneously rather than optimizing a single metric.