Thermal and electrical performance evaluations of series connected Li-ion batteries in a pack with liquid cooling

Lithium-ion batteries are widely used in electric and hybrid electric vehicles due to their wide nominal range and high power densities. However, operating temperature, which has a pronounced effect on battery thermal performance and electrical performance, needs to be maintained within a specified range. In the present study, a Li-ion battery pack has been tested under constant current discharge rates (e.g. 1C, 2C, 3C, 4C) and for a real drive cycle with liquid cooling. The experiments are performed using cold plates at 10 degrees C, 20 degrees C, 30 degrees C, and 40 degrees C coolant temperatures to obtain thermal and electrical parameters. For this, three 20Ah LiFePO4 prismatic cells are connected in series and a battery thermal management system is designed and developed for liquid cooling. To measure the temperature variation, 18 thermocouples are installed on the principal surface of all three cells: i.e., six on each cell. The results show that the battery pack temperature can be maintained within the required range at all four selected discharge rates with the coolant at 30 degrees C. The discharge capacity of the battery pack increases with increasing coolant temperature and is found to achieve a maximum of 19.11 Ah at a 1C discharge rate with the coolant at 40 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.