Hithium completes world’s first open-door fire test for grid-scale BESS

Amid growing global scrutiny over the safety of energy storage systems, Hithium has successfully conducted the world’s first open-door extreme fire test, establishing a precedent for safety validation in the sector. The test offers a high-stakes technical model to inform future product safety standards.

The subject of the test was Hithium’s self-developed ∞Block 5MWh liquid-cooled battery storage system. The trial was led by global safety certification agency UL, and witnessed by a U.S.-certified fire protection engineer and customer representatives. It adhered strictly to both the UL 9540A and NFPA 855 standards.

The test was designed to simulate four extreme fire conditions, challenging the structural and thermal resilience of the system under real-world emergency scenarios.

The first challenge is to simulate open-door under overload oxygen. Breaking from traditional closed-door testing protocols, the battery cabinet remained fully open throughout the test, creating an unconstrained burn environment with intensified oxygen flow. Despite these harsh conditions, the cabinet’s structure remained intact, demonstrating superior heat resistance.

The second challenge is to minimize spacing and test thermal isolation. The cabinets were positioned just 15cm apart, arranged both side-by-side and back-to-back. Subjected to temperatures reaching 1,300°C, none of the adjacent cabinets experienced thermal propagation, validating the system’s near-field thermal isolation design.

The third is to verify passive protection with no active fire suppression. All external fire suppression systems were deactivated. Relying solely on passive internal fireproofing, the unit endured a full 15 hours of continuous burning without structural failure or uncontrolled escalation.

Hithium decided to have all cells 100% charged (SOC) to simulate the most dangerous condition for thermal runaway. Even under these extreme conditions, the system avoided explosion or collapse, proving the integrity of its electro-thermal-structural containment design.

The test ran continuously for 15 hours. The core unit maintained structural integrity, and no thermal propagation was detected in the three neighboring units. This comprehensive validation underscores the ∞Block system’s ability to perform under “open-door, minimal spacing, extended combustion” scenarios.

Industry experts hailed the trial as a “qualitative leap” in energy storage fire safety testing, significantly increasing difficulty across fire dynamics, spatial constraints, charge state, and response conditions. The results not only enhance the credibility of safety claims but offer a replicable framework for establishing more practical, real-world safety benchmarks.

The company attributes its successful performance to its proprietary three-tier protective architecture spanning cell, module, and system levels. Hithium views this as the cornerstone of next-generation battery system safety, driving the industry from cell-level safety toward holistic system-level resilience.

Founded in 2019, Hithium has emerged as a major global supplier of battery storage systems. According to research firm Infolink’s latest market data, the company ranked 4^th globally in energy storage battery shipments in 2024, delivering 35.1 GWh.