TU Graz scientists have shown how aged EV batteries decrease the likelihood of accidental battery fires, thus making them safer than their new-age counterparts.
The basis of this four-year, ‘SafeBattery’ study lies in the efforts taken by project manager Christian Ellersdorfer and his team to determine how EV batteries perform and react under crash loads. Other big names involved in this project are AVL, Audi, Porsche and Mercedes Benz.
According to Ellersdorfer, the older an EV traction battery is, the lower the danger it poses.
For this study, he and his team put the battery through a series of scenarios that it would experience in the course of its life.
These included vibrations and strong accelerations caused by parking bumps, serious accidents, and the constant charging and discharging of batteries.
With the help of crash tests, simulation models and calculation methods, the SafeBattery team was able to determine that vibrations and accelerations hardly affect the behavior of batteries.
What does affect them is the constant charging and discharging of the battery. Battery cells aged in this way have a higher stiffness under mechanical load.
“But the changes don’t necessarily mean that batteries become more dangerous with age,” intones Ellersdorfer.
“On the contrary. The sum of the influences makes them safer over time because they also lose electrical energy.”
According to the scientist, cells with a strongly reduced capacity content have a weakened course of the so-called thermal runaway after an internal short circuit, thus decreasing the likelihood of accidental battery fires.
Apart from benefiting the automotive industry, the SafeBattery consortium is going one step further to determine how these EV batteries can be repurposed for second life use.
This will be foreseen under the SafeLIB project (2021-2025) that will determine valid parameters in the area of safety for stationary energy storage and machine tools.
Ellersdorfer and his team will use the world’s only test bench technology for battery safety at the Battery Safety Center Graz to this end.
Image and content: Lunghammer/TU Graz
