Electric vehicles (EVs) are increasingly populating our streets. While often perceived as risky due to their high-voltage batteries, statistics show that they are actually less likely to catch fire than conventional petrol or diesel cars. Data from the Swedish Civil Contingencies Agency confirms this: only 23 fires occurred among 611,000 electric cars, an incident rate of less than 0.01%, compared to 0.08% for internal combustion engine (ICE) vehicles of similar age. EVs also frequently achieve higher safety ratings in crash tests. Yet, safer does not mean completely safe. Fires caused by battery thermal runaway can still occur, and once ignited, they are harder to extinguish than ICE vehicle fires.

While it is easy to measure how far a vehicle can travel on a single charge, how fast it accelerates, or how quickly it can recharge, there has long been no clear way to measure battery safety. Performance can be tracked with indicators such as State of Health (SOH) or State of Power (SOP), but the question “How safe is this battery right now?” has no simple, measurable answer.

This question is addressed by the RELIABAT project, led by Battery4Life GmbH in collaboration with researchers at Graz University of Technology’s Vehicle Safety Institute, together with MAGNA STEYR Fahrzeugtechnik GmbH & Co KG, Infineon Technologies AG, and AVL DiTEST GmbH. The project develops the concept of State of Safety (SOS), aiming to establish measurable indicators that reflect the intrinsic safety of a battery.

Within the project, seven safety indicators have been defined to quantify both the likelihood and potential severity of battery thermal runaway, which can lead to fires. The indicators capture different aspects of battery safety and together provide a comprehensive picture of the battery´s safety state. For example, one key indicator is the onset temperature, the temperature at which exothermic reactions are spontaneously triggered within the battery. Depending on the cell chemistry, the onset temperature in lithium-ion batteries typically ranges from 80 °C to 150 °C. Under certain battery conditions, however, the onset temperature can drop and move closer to the normal operating temperature range of EVs. While such conditions remain rare, they indicate changes in the battery’s safety margin and therefore represent an important parameter for assessing battery safety. Monitoring changes in the onset temperature provides valuable information about the battery’s evolving safety state over its lifetime. Defining measurable safety indicators is only the first step. Researchers also investigate how SOS evolves over time, since driving habits, environmental conditions, and battery aging all influence these safety parameters. A deep understanding of battery aging and real-world battery behavior is therefore essential. Building on this knowledge, predictive models are being developed that link measurable electrical properties, such as voltage and current already monitored by modern battery systems, to the safety indicators. These models enable continuous monitoring and proactive assessment of battery safety throughout the battery’s lifecycle. By combining these approaches with other ongoing Battery4Life projects, batteries could one day communicate their SOS, allowing users and manufacturers to take preventive action and use batteries longer, more efficiently, and with greater confidence.

Impact and effects

The development of the SOS lays the foundation for a standardized and measurable approach to battery safety. Scientifically, it provides a comprehensive framework to understand intrinsic battery safety. Industry gains new tools to assess and predict safety in real-world applications, supporting safer and more efficient battery operation. For society, SOS strengthens trust in electrified mobility, extends battery lifetime through informed use, and contributes to a safer and more sustainable energy future.

The concept of State of Safety reaches far beyond EVs. Any application using lithium-ion batteries, including laptops, smartphones, and stationary energy storage systems, could benefit from continuous monitoring and proactive safety management. In the long term, SOS supports a more reliable and sustainable energy transition while enabling safer and smarter use of battery technologies.

We would like to express our sincere appreciation to UAR – Upper Austrian Research GmbH for the funding approval within their HR Excellence Initiative. The international research stay of David Fixl at Rimac Technology will provide an important opportunity for advanced scientific exchange, international cooperation and the further development of industry relevant expertise in […]

We would like to express our sincere appreciation to UAR – Upper Austrian Research GmbH for the funding approval within their HR Excellence Initiative.

The international research stay of David Fixl at Rimac Technology will provide an important opportunity for advanced scientific exchange, international cooperation and the further development of industry relevant expertise in the field of battery technologies.

This initiative makes a valuable contribution to strengthening individual research excellence while enhancing the international visibility of the UAR Innovation Network and supporting the long-term sustainability of the research and innovation ecosystem in Upper Austria.

We wish David a successful and productive research stay!

We are pleased to share that the second board meeting of the RELIABAT project was kindly hosted by AVL DiTEST. A sincere thank you for the warm welcome and excellent organization!

RELIABAT is dedicated to defining the State of Safety (SOS) for batteries, an important milestone for enhancing safety, reliability, and extending the service life of lithium-ion batteries.

It was inspiring to experience the strong commitment and open exchange among all project partners. In parallel to these valuable discussions, experimental measurements are currently underway. We are excited to announce that first results and further insights will be shared soon.

A big thank you to all partners AVL DiTEST, Infineon Technologies, Magna International, and Vehicle Safety Institute – TU Graz for the insightful discussions and outstanding collaboration. We look forward to the next steps together.

We are delighted to welcome two new employees to our team – Silvia Larisegger and Moritz Günthner! Silvia and Moritz will further expand our team in Research Area 3 and bring valuable expertise into our projects.

Silvia Larisegger joins us as Area Manager. With her PhD in Technical Chemistry, Silvia will take on scientific leadership and strengthen our competencies in Area 3.

Moritz Günthner enriches our team as a Researcher. Among other topics, Moritz as a mechanical engineer, will focus on diagnostic charging profiles for batteries and their utilization for damage detection and beyond.

We are convinced that both of you will be a great enrichment to our team and look forward to working together, exchanging ideas, and many successful projects ahead!

Welcome to the Battery4Life team!