Experimental investigation on using the electric vehicle air conditioning system for lithium-ion battery thermal management

It is investigated a lithium-ion battery thermal management (BTM) system using the electric vehicle (EV) air conditioning refrigerant to cool the battery pack directly. In the system, basic finned-tube heat exchanger structure and a special aluminum frame are adopted to design the battery pack thermal management module with lithium-ion batteries of cylindrical shape. The module is then integrated into the electric vehicle air conditioning system using two electronic expansion valves for the automatic control of the pack's temperature with self-programmed control software. Experimental results show that the BTM system can control the battery pack's temperature in an appropriate preset value easily under extreme ambient temperature, as high as 40 °C. In addition, through the refrigerant circuit optimization it can reduce the temperature non-uniformity inside the battery pack. The temperature difference within the pack is less than 4 °C in the constant discharge rate of 0.5 C, 1 C, 1.5 C laboratory tests, and 1.5 °C in road drive tests.