Investigation of Current Sharing and Heat Dissipation in Parallel-Connected Lithium-Ion Battery Packs

This paper adopts a circuit model with temperature-dependent parameter values to investigate the current unbalance risk in parallel-connected lithium-ion (Li-ion) battery cells and uses this circuit model to calculate heat dissipation. The paper first investigates use of the battery model to explain the impact of temperature on current unbalance in parallel-connected Li-ion battery cells. Experimental results confirm the model's accuracy, as well as demonstrating the serious effect that the negative temperature coefficient of Li-ion cells can have on current unbalance, particularly at low temperatures below 0 degrees C. The second half of the paper focuses on the use of a calorimeter to collect battery heat dissipation data that is then used to confirm the battery model parameters derived from Electrochemical Impedance Spectroscopy (EIS). The effectiveness of the battery circuit model for estimating the pack heat dissipation is experimentally verified.