The storage of large quantities of Li-ion batteries is necessary in various industries and warehouses around the world. However, an increasing number of fire incidents is continuing to raise questions on the risk and safety of storage configurations of Li-ion batteries, because the fires have the potential to spread rapidly with minor chance for firefighting to quickly control the large-scale battery fires. In the consequence, these fires can release great amounts of toxic products that impact the environment and lead to major economic losses for the affected industry. Thus, a research project is currently underway in Germany to investigate the controllability of large destructive fires in factory buildings with battery systems and its fire spread models (project title: BEGIN-HVS, German name: “Beherrschbarkeit von Großschadensfeuern in Industriehallen mit dem Gefahrgut Hochvoltspeicher und deren Ausbreitungsmodelle”). The project coordinator is the City of Munich – Fire Department with the TU Braunschweig conducting the experimental testing and BAM running the numerical investigations.

In the research project, the burning behaviour of Li-ion BEV batteries in the storage situation was investigated experimentally in three stages. In the first test series, BEV modules (3-9 kWh) were triggered into thermal runaway and the burning behaviour was investigated in a calorimeter test stand. In the second and third test series, up to eight full-size BEV battery systems (50-110 kWh) were placed in different storage configurations inside of a large-scale calorimeter. Again, the fire was triggered in these batteries and the burning behaviour of the individual full-size BEV-battery systems as well as the fire spread between multiple full-size BEV-battery systems was recorded.

All experimental investigations were carried out at TU Braunschweig in the center for fire research “ZeBra” (German name: “Zentrum für Brandforschung”). Opened in 2023, this Advanced FireLab provides experimental research opportunities in a large hall and laboratories for investigation the fire dynamic: From small samples at laboratory-scale (cone-calorimeter, etc.) to medium-scale tests (room-corner test, battery calorimeter) and large, full-size experimental setups (e.g., 4-storey fire house, experimental facade with 12 m height and open floor on a scale at 9 x 9 m) with maximum capacity of 20 MW. The research project utilized the battery calorimeter (output capacity of up to 5 MW) in the first test series, where individual battery modules were investigated. For test series two and three, the storage configurations of multiple full-size BEV battery systems were setup on the large floor scale of the open floor calorimeter. This calorimeter is designed for outputs of up to 20 MW in order to accommodate multiple BEV batteries burning simultaneously in the 8-battery storage scenario in test series three.

The research project “BEGIN-HVS” is funded by the German Federal Ministry of Education and Research (BMBF) under the program “Forschung für die zivile Sicherheit” (www.sifo.de).