»AIR«: Drive battery inspection using X-rays

The complete X-ray inspection of fully assembled vehicles can currently only be carried out under laboratory conditions at a few locations worldwide - including at the X-ray Technology Development Center at Fraunhofer IIS using XXL computed tomography. However, the procedure is complex and costly, so its use is currently reserved for companies that check safety-relevant components in particular during the development process.

The newly developed AIR system (traction battery inspection using X-rays) changes this: the system makes it possible to visually assess the mechanical integrity of battery modules by taking an X-ray image of the vehicle and the traction battery mounted in the underbody. To do this, the vehicle is driven into the measurement system - the measurement setup is reminiscent of a classic car wash.

The X-ray images are taken from a bird's eye view. The X-ray source positioned above the vehicle emits a fine X-ray beam that passes through the vehicle, including the battery, and is collected and processed by a detector positioned on the ground. Even in fully encapsulated battery modules, a detailed view of the battery is possible in order to make statements about the mechanical condition of individual battery cells, the battery frame and other features. This information can be used, for example, to analyze and evaluate individual components of the vehicle or battery with regard to position, alignment or integrity.

© Fraunhofer IIS/Christina Müller
The measurement setup of the AIR X-ray system is reminiscent of a classic car wash: the X-ray source positioned above the vehicle emits a fine X-ray beam that passes through the vehicle, including the battery, and is collected and processed by a detector positioned on the ground.

Great market potential

© Fraunhofer IIS
Complete scan of the battery modules of an electric vehicle with the AIR portal. The individual cylindrical battery cells and their correct position are clearly visible, ruling out the possibility of damage.
© Fraunhofer IIS/Christina Müller
Michael Salamon, group manager for high-energy X-ray systems, presents the new testing option for electric vehicle batteries.

The prevalence of fully electric vehicles has risen sharply since 2020. According to figures from the Federal Environment Agency, only around 63,000 units were sold in 2019, compared to around 524,000 vehicles in 2023, almost nine times as many. As a result, the market share of fully electric vehicles also increased significantly from 1.8% in 2019 to 18.4% in 2023 within four years. Even though there is still a long way to go before the German government's target of 15 million electric vehicles by 2030 is reached, electromobility is becoming increasingly popular.

So far, the well-founded assessment and condition evaluation of the traction battery - for example of a used or damaged vehicle - is only possible in a very rudimentary way. In particular, this is dampening confidence in the technology and inhibiting the used car market in the electric sector.

The AIR X-ray system has the potential to become the standard tool for the objective assessment and evaluation of electric vehicles - after all, the traction battery is by far the most expensive component of the vehicle. The new system is specifically designed to meet the requirements of the fastest and most cost-effective testing possible, which promotes uncomplicated accessibility of the technology and enables rapid market penetration. The measurement time per vehicle is currently around ten minutes, which allows uncomplicated integration into existing testing processes.

Comments on the project

Michael Salamon, Fraunhofer IIS: »For the first time, AIR technology makes it possible to carry out a detailed inspection of the vehicle underbody quickly and easily. By focusing the technology on the life cycle of vehicles, Fraunhofer IIS is doing pioneering work as part of a strategic initiative to increase confidence in the still young technology and thus promote the emerging used car market, among other things.«

Prof. Klaus Böhm, Munich University of Applied Sciences: »AIR has the potential to revolutionize the preparation of expert opinions in the context of electromobility - and beyond. The described limitations of the methods used to date can be significantly expanded by incorporating AIR into a multidisciplinary approach. This will contribute to a reduction in repair costs for electric vehicles. More accurate and reliable appraisals can also lead to more predictable used car processes and lower insurance premiums for electric vehicles.«