Li-ion batteries have been proven to be an unmatched candidate for Electric Vehicles. Some of the distinct benefits of Li-ion batteries are excellent energy density, high charge and discharge rates, longer lifespan, negligible memory effect with very little self-discharge rates. It is evidently known that the performance of the battery is significantly affected by operating temperature. The high susceptibility of the batteries to the operating temperature makes the use of some Thermal Management System (TMS) so that an optimum working temperature can be maintained. Herein, a detailed thermal investigation of a battery pack made up of four 20 Ah cells connected in series has been conducted. Both air cooled and phase change material (PCM) enhanced thermal management system for a discharge rate of 3C and 4C for the pack have been tested. A detailed parametric variation of the inlet velocities, inlet-outlet locations and PCM have yielded significant comparative results between the active and the passive methods. The temperature rise for the battery pack during a 4C discharge, has been found to decrease by 77.76% for the passive TMS and by a maximum of 57.9% for forced air cooling.