When the EV battery is X-rayed

Fraunhofer Development Center for X-Ray Technology, a division of the Fraunhofer Institute for Integrated Circuits IIS, has introduced a novel testing method for electric vehicle batteries. In collaboration with the University of Applied Sciences Munich, the scientists presented the research project "AIR" (Antriebsbatterieinspection using Röntgen).

Important Step

Currently, the complete X-ray of fully assembled vehicles can only be achieved in a few places worldwide under laboratory conditions – including the X-ray Technology Development Center of the Fraunhofer IIS in Fürth. However, the procedure is complex and costly, so its use is currently reserved for companies that mainly inspect safety-relevant components during the development process. This changes with the newly developed AIR system: The system enables the visual assessment of the mechanical integrity of battery modules by taking an X-ray image of the vehicle and the drive battery mounted in the underbody.

For this purpose, the vehicle is driven into the measuring system – the setup resembles 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 captured and processed by a detector positioned on the floor. Even in fully encapsulated battery modules, a detailed view of the battery is possible to make statements about the mechanical condition of individual battery cells, the frame, and other features. The new system is specially designed to meet the requirements of a fast and cost-effective inspection.

Objective Evaluation Possibilities

Until now, the thorough assessment and condition evaluation of an electric vehicle's battery has only been possible in a very rudimentary way. Experts like Prof. Klaus Böhm from the Munich University of Applied Sciences have had to largely rely on diagnostic tools from manufacturers.

“In practice, this essentially works in the same way as one knows from the fault diagnosis of reasonably modern vehicles. Plug it in, and a diagnostic software reads out any possible problems. In some cases, this is done over several days during driving with certain concepts. In the event of more serious accidents, for example when the airbag in the vehicle has been deployed, manufacturers have very clear procedural instructions. In general, the traction battery must be mandatorily replaced, even if it has suffered no damage,” says Prof. Böhm.

On one hand, such strict safety precautions are currently essential to ensure the operational safety of the vehicles—and therefore also the safety of occupants and other road users. On the other hand, from the perspectives of sustainability and resource conservation, it is questionable to recycle harmless, functional batteries.

“There is a significant need in the market for an additional objective evaluation possibility for vehicle batteries. That’s why we have been researching X-ray systems for many years, which could play a central role in the assessment of high-performance batteries,” says Michael Salamon, group leader at the Development Center for X-ray Technology at the Fraunhofer IIS.