UTAC supports EV battery safety with thermal propagation testing

Electric vehicles, automotive safety systems, and battery engineering are facing stricter regulatory requirements as thermal runaway risks remain a critical concern. In this context, UTAC is supporting the implementation of updated thermal propagation testing procedures aligned with the revised UNECE R100 framework, which entered into force in September 2025 and is expected to become mandatory for new vehicles from September 2027, subject to European Commission publication.

The updated regulation does not introduce entirely new test methods but reinforces and standardizes existing procedures used to evaluate battery safety. The objective is to harmonize testing approaches across the industry while ensuring consistent and high safety levels for electric vehicle battery systems.

Reinforced testing framework for thermal propagation
The revised requirements focus on assessing how thermal runaway propagates within a battery system under controlled conditions. Instead of isolated cell-level validation, the framework emphasizes system-level behavior and reproducibility of results.

Among the validated methodologies are controlled heating tests and mechanical intrusion scenarios. These include the use of external or internal heating elements to induce rapid temperature increases, as well as nail penetration tests designed to simulate internal short circuits caused by cell damage. These approaches enable engineers to observe how failures initiate and propagate within battery modules.

Minimum safety delay for occupant protection
A key requirement of the updated regulation is ensuring a defined delay between the onset of thermal runaway and the occurrence of critical events such as explosion or uncontrolled propagation. The framework specifies a minimum delay of five minutes, allowing vehicle occupants sufficient time to evacuate safely.

This requirement introduces a measurable performance criterion for battery system design, influencing cell chemistry selection, module architecture, and thermal management strategies in electric vehicles.

Testing infrastructure and industry collaboration
UTAC conducts these tests at its facilities in Linas-Montlhéry and Millbrook, where controlled environments allow repeatable validation of battery performance under failure conditions. The organization also collaborates with industry stakeholders, including the PFA and regulatory bodies such as the DGEC, to support the development and implementation of standardized safety procedures.

The structured testing framework may also extend beyond automotive applications to other battery systems, reflecting broader safety considerations as electrification expands across sectors.

By reinforcing existing methodologies and introducing quantifiable safety criteria, the updated UNECE R100 framework represents a significant step in improving electric vehicle safety, particularly in managing thermal propagation risks at the system level.

Edited by Natania Lyngdoh, Induportals Editor — Adapted by AI.

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