The BEV fire that occurred in South Korea in August 2024 and the resulting extensive damage seems to have become a major topic of discussion not only in Japan but also in other major countries where BEVs are being introduced. Under such circumstances, another BEV issue is being addressed in Korea in October 2024. So to speak, “Crash Management System (CMS)”, a technology related to crash control, is beginning to attract attention due to BEV crashes and the resulting fire accidents.

BEVs are generally designed structurally to protect the battery pack from front and rear collisions (to reduce crash energy), with the battery pack positioned in the center of the vehicle and the eAxle or trunk space in the front and rear. However, in addition to such front-rear collisions, there are cases where the battery pack is directly damaged by objects under the vehicle body, i.e., on the road (falling objects, road damage, etc.). In such cases, it is difficult to mitigate the impact from a collision because the battery pack is directly exposed to the roadside, and most of the impact is received in its entirety, leading to damage not only to the pack, but also to the cells and modules, and in the worst case, a fire.

The upper part of the vehicle, based on the battery pack, has a cabin, or passenger compartment, which can protect the battery pack, but the lower part has no protection for the pack. Some manufacturers try to suppress impact by attaching a cover such as those used on existing engine cars. Of course, there are also proposals to reinforce the pack housing itself with ultra-high strength materials or CFRP/GFRP materials.

The reason I bring this up is that on October 2, 2024, a BEV crash and fire accident occurred in Suwon, Gyeonggi-do, South Korea, due to a falling object. A Hyundai Ioniq5 was driving on a public road at the time, and a falling object (iron material, reportedly about 7 cm in size), presumably from a truck, impacted the battery pack after colliding with the right side bumper of the Ioniq5. Smoke and fire immediately broke out, but it was extinguished in about 2.5 hours, burning only the battery pack.

In order to raise the safety of BEVs, various innovations are needed. Until now, the focus has been on thermal management, but from now on, how to protect the battery pack from collision and impact will also become important. To this end, it is necessary to seriously consider how to design, adopt materials, etc., to create optimal packs.