The growing popularity of electric vehicles (EVs) has highlighted the importance of efficient battery thermal management systems (BTMS) for EV batteries. High temperatures can harm not only battery performance but also lifespan. This study examined a 4P3S battery module at 30°C ambient temperatures, finding a strong correlation between the state of charge (SOC) and battery temperature, especially at high discharge rates nearing the operational limit. A unique Loop Heat Pipe (LHP) design is developed in the present work consist of De-ionized (DI) water as the working fluid, separate vapor and liquid lines to reduce heat losses, and an aluminium block act as a heat sink. The 4P3S battery module with the LHP system demonstrated a 45% reduction in maximum cell temperature when compared 4P3S battery module without cooling at a 2C discharge rate. Furthermore, the LHP effectively controlled the temperature gradient within a narrower range of 2°C to 4°C.