A parametric analysis has been conducted for the phase change material (PCM)-air cooled battery pack. The system is composed of 26650 lithium-ion LiFePO4 batteries enclosed by PCM. A one-dimensional thermal model for the PCM domain is developed using the enthalpy method. The finite volume method is employed to solve the energy equation for both cell and PCM domain. The developed computational algorithm has been validated as a result of the simulations for the same conditions with the literature. The discharge process of the batteries has been investigated for 2C, 3C, and 5C rates. Thermal analyses have been performed for passive (natural convection) and active cooling (forced convection). It is aimed to keep the temperature of the battery cell under critical levels. A parametric investigation for crucial parameters like PCM layer thickness, the thermal conductivity of the PCM, arrangement of the batteries has been performed. Simulations have been conducted for the constant air velocity and the pumping power. Thanks to the constant pumping power analysis, thermally best-performing configuration have been sought by eliminating the hydrodynamic effect.