The battery is the last wearing part of an electric vehicle and accounts for a significant proportion of its cost (up to 30%). To manage this asset well, both the most accurate battery sizing possible and an assessment of its utility in resale or transfer to a post-automotive application are required. System sizing is typically based on cell manufacturer specifications and accelerated aging tests, while residual capacity measurement is often considered useful for determining aging status and thus utility. With regard to real applications, which are characterized by diverse combinations of different loads, these approaches have one problem in common: they do not, or only inadequately, represent the range of loads and their interaction. A vehicle battery is neither operated permanently at a constant 1C and 100 % DOD (cell manufacturer’s specification; capacity measurement) nor permanently at very high or low temperatures (accelerated aging tests). This directly leads to the objective of the project to learn the following characteristics directly from the field data:
- the aging behavior to determine the stress factors and their interactions,
- the aging condition without additional capacity tests during operation, and
- the usage behavior for application-specific service life prediction.
This also makes it possible to redefine the end of life of a battery as the point in time at which a battery can no longer meet the requirements of its respective application.
To achieve these goals, the TU Berlin and the Fraunhofer Institute for Transportation and Infrastructure Systems are working closely together within the project and are also contributing their findings to the competence cluster Battery Utilization Concepts and the accompanying project greenBattNutzung.