Sensitivity analysis and development approach of HV battery lifetime for complete vehicle integration

The lifetime and aging of the high-voltage battery are among the key factors influencing the end customer’s decision to choose an electric powertrain over a conventional one. Consequently, battery aging has become a critical aspect of overall vehicle development to ensure that vehicles meet customer expectations, for example risk of repair costs or resale value. Additionally, legal regulations (e.g. EU7) will define minimum warranty requirements for high voltage batteries. These circumstances establish battery lifetime and aging as an essential development target at complete vehicle level. The paper presents a method for the development process of a lifetime target from complete vehicle perspective. The approach involves the generation of a representative monthly electrical power and temperature profile for the high voltage battery. Based on a monthly user routine, ambient temperature profile and charging behavior, a vehicle-specific battery power profile is created using energy flow simulation. The simulation also includes the high voltage battery’s state of charge and temperature. Next, a generic battery cell aging model is applied to estimate the impact on the battery’s state of health over its lifetime, using the generated power and temperature profiles. This allows for a prediction of the aging behavior of the high-voltage battery. Using these tools with its capability for aging prediction, several sensitivity studies have been conducted (e.g. impact on charging behavior, ambient temperature and vehicle operating strategy) to identify the main impacts influencing battery aging. The results are restored to improve the overall method and to support the identification of countermeasures for improving of the high voltage battery aging. The simulation tool and the results of the sensitivity analyses will be presented in the paper.