HiTHIUM completes open-door fire test of 6.25MWh LDES system

HiTHIUM has completed what it described as the world’s first open-door, large-scale fire test of a 6.25MWh long-duration energy storage (LDES) system, validating safety performance under extreme conditions. The test was conducted under the supervision of UL Solutions and U.S. Authorities Having Jurisdiction, and was carried out in compliance with the latest UL and National Fire Protection Association (NFPA) safety standards.

The test focused on HiTHIUM’s ∞Power 6.25MWh system equipped with ultra-large 1175Ah battery cells. It built on an earlier validation exercise conducted on a 5MWh system and was designed to assess system-level safety at higher energy density. The test simulated a worst-case scenario, with container doors kept fully open to maximise oxygen supply and flame exposure, adjacent containers placed with only 15 cm spacing, the system operating at 100% state of charge, and all active fire suppression systems disabled.

According to the company, the system demonstrated stable safety performance across three key areas. Controlled venting during thermal runaway prevented explosive pressure build-up, with no explosions or debris ejection observed. Fire-resistant materials and reinforced structural design confined the fire to a single unit, with no thermal propagation to adjacent containers. The reinforced steel frame and internal partitions also maintained structural integrity after prolonged exposure to high temperatures, with no major deformation reported.

HiTHIUM said the test represents a milestone in safety validation for high-energy-density, long-duration energy storage systems. The company added that the results support the safe, large-scale deployment of LDES technologies and contribute to the development of higher global safety standards as system capacities scale beyond 6.25MWh.

Photo: Fire test site. Credit: HiTHIUM