Effect of Battery Temperature on Fuel Economy and Battery Aging When Using the Equivalent Consumption Minimization Strategy for Hybrid Electric Vehicles

Battery temperature variations have a strong effect on both battery aging and battery performance. Significant temperature variations will lead to different battery behaviors. This influences the performance of the Hybrid Electric Vehicle (HEV) energy management strategies. This paper investigates how variations in battery temperature will affect Lithium-ion battery aging and fuel economy of a HEV. The investigated energy management strategy used in this paper is the Equivalent Consumption Minimization Strategy (ECMS) which is a well-known energy management strategy for HEVs. The studied vehicle is a Honda Civic Hybrid and the studied battery, a BLS LiFePO4 3.2Volts 100Ah Electric Vehicle battery cell. Vehicle simulations were done with a validated vehicle model using multiple combinations of highway and city drive cycles. The battery temperature variation is studied with regards to outside air temperature. Multiple outside air temperatures are simulated, each with six ECMS penalty factors for each combination of drive cycles. Battery aging is evaluated using a semi-empirical model combined with the accumulated Ampere-hour throughput (Ah-throughput) method. The simulation results provide insight into how temperature affects the battery capacity, battery aging, and fuel economy. The paper concludes with a discussion on the balance between fuel economy and battery aging in different temperature conditions.