Efficient thermal management is crucial for lithium-ion battery safety and longevity in Electric Vehicles (EVs). This study presents a numerical investigation and experimental validation of liquid cooling strategies for NMC lithium-ion battery modules, comparing serpentine (Configuration 1), parallel (Configuration 2), and parallel/counter-flow hybrid (Configuration 3) layouts. A custom-built 4-cell test rig validated against CFD simulations showed close agreement, with relative deviations below 0.6%, confirming model reliability. Under regulated flow conditions, clear differences in thermal and hydraulic behavior were observed. Configuration 1 exhibited the highest thermal stress, with peak temperatures reaching 75.7 \(\:^\circ\:C\) (cell 7) and 74.1 \(\:\:^\circ\:C\) (cell 18) due to downstream heat accumulation and limited contact area, alongside the largest temperature difference (ΔT = 11.0 K) and highest pressure drop (27.3 Pa). Configuration 2 reduced peak pack temperature to 70.6 \(\:^\circ\:C\) at cell 18 (6.7% lower vs. Configuration 1) and 64.7 \(\:^\circ\:C\) at cell 7 (14.8% lower), achieving the best intra-cell uniformity (σ = 0.47 K, CV = 5.6%) and lowest pressure drop (9.1 Pa). Configuration 3 offered the most balanced cooling, lowering maximum cell temperature by 7.6% compared to Configuration 1 and 0.9% compared to Configuration 2, while the maximum temperature of cell 18 decreased by 11.8%. It achieved the narrowest inter-cell ΔT (4.1 K), a 62.5% and 11% reduction versus Configurations 1 and 2, respectively, with the lowest σ = 1.0 K (CV = 0.32%). Overall, serpentine cooling is simple but thermally inefficient, parallel flow is the most energy-efficient, and the hybrid parallel/counter-flow design delivers the best overall thermal balance while lowering the required pumping power by about 89%, making it the most suitable layout for safe and reliable EV battery operation.
