A Study on effect of coolant flow rate on steady-state thermal resistance of a 48 V lithium iron phosphate battery pack under dynamic duty cycles

In the growing lithium-ion battery market, an efficient battery simulation plays a crucial role in assessing performance and lifetime of Li-ion battery products. Computationally thermal models are in high demand for the battery simulation. In this work, a 1-D simplified thermal model considering cell heat generation was developed to correlate the steady-state thermal resistance under dynamic duty cycles for a 48 V lithium iron phosphate (LFP) battery pack with fourteen cells in series. The thermal resistance was correlated based on the proposed thermal model and thermal data collected by thirty-three thermal sensors placed in the thermal experiments under a representative dynamic drive cycle profile used in practical applications. Also, the influence of the coolant flow rate on the steady-state thermal resistance between the cell and the coolant was comprehensively studied. It was found that the cell-averaged steady-state thermal resistance decreases from 1.31 ∼ 1.97 K/W to 0.88 ∼ 1.46 K/W as the coolant flow rate increases from 0.5 L/min to 15 L/min. Furthermore, the ‘Tab’ and ‘Bottom’ region was found to have the largest and smallest averaged steady-state thermal resistance, respectively. This thermal resistance correlation work is expected to benefit a computationally efficient battery thermal and electrical performance, and lifetime prediction.