UPS Battery Safety Fire and Explosion Hazard Assessment

This technical report presents a comprehensive evaluation of fire and explosion hazards associated with lithium-ion batteries (LIBs) used in uninterruptible power supply (UPS) systems, particularly in data center applications. The report outlines the findings from large-scale fire testing conducted by FM in collaboration with Delta Electronics Inc. and Equinix. Phase I testing revealed that thermal runaway (TR) could propagate across adjacent modules, leading to significant fire risks. In response, the UPS system was redesigned to reduce heat transfer and enhance sprinkler cooling effectiveness. Phase II testing confirmed that the modified system successfully contained TR within the initiating module, with neighboring modules remaining undamaged. Additionally, an explosion hazard analysis was performed, indicating that under specific conditions, the risk of explosion is minimal, provided adequate room volume and ventilation are maintained. The report concludes that the developed fire test method effectively captures realistic failure scenarios, leading to significant improvements in fire safety performance.