Battery Heat Load Estimation and Modeling its Thermal Management Using Air Conditioning Cooling System of an Electric Vehicle

The performance of lithium-ion batteries and its service life depends on its operating temperature. Operating the battery above 45 °C degrades the performance of the battery and reduces its service life. The high-temperature operation also leads to thermal runaway. So there is a need to monitor the operating temperature and voltage output of the battery using a battery thermal management system to ensure its safety. Battery Thermal Management System (BTMS) is a part of the battery management system. The effectiveness of the battery thermal management system depends on the battery pack design, battery chemistry, vehicle operating characteristics and ambient conditions. In this work, a refrigerant-based BTMS is modeled using MATLAB Simulink. Refrigerant R134a used in the air conditioning system of an Electric Vehicle is used as an evaporative cooling medium to cool the batteries. The battery pack is submerged in the pool of refrigerant for cooling and to control the battery temperature the refrigerant level is varied according to the battery’s electrical load. The additional load on the air conditioner compressor for cooling the lithium-ion batteries of an EV is calculated to study the effect of the cooling system on vehicle range