Battery Pack-Level Fire Safety Proven in SigenStack Stress Test

To rigorously validate the safety performance of its commercial and industrial energy storage system, under extreme fire scenarios, Sigenergy recently completed a full-scale combustion test on its SigenStack system. Despite the complete removal of active safety mechanisms, the system successfully contained the fire within a single battery pack, preventing thermal runaway or flame spread to adjacent modules or racks.

Fire Containment Validated at Battery-Pack Level

This test replicated one of the most extreme conditions for energy storage systems: a sustained open-flame fire triggered by cell-level thermal runaway. To push the system to its limits, Sigenergy disabled all active protections—including built-in fire suppression modules, pressure relief valves, and software-based sensors for temperature and smoke—relying solely on the system’s passive structural defenses. Heat was applied to 25% of the cells within a battery pack to simulate worst-case ignition.

The test setup followed real-world installation constraints, with only 20 cm spacing between battery racks front-to-back and 30 cm side-to-side, simulating dense deployment scenarios. Full-size production units were used to ensure meaningful engineering data.

During testing, the targeted cell temperature peaked above 300°C. The directly ignited pack’s surface reached 264.65°C, yet no thermal runaway occurred in any internal cells. All surrounding packs remained below 31°C. After approximately 30 minutes, flames subsided and combustion remained localized within the affected pack, without propagating to adjacent modules.

These results demonstrate that SigenStack can successfully contain even severe internal fires within a single battery pack, highlighting its robust thermal suppression and structural integrity.

Post-test teardown confirmed:

• No short circuits between cells
• No BMU (Battery Management Unit) ignition
• No system-level voltage collapse
• No busbar arc faults or secondary failures
• No venting or damage to the surrounding battery packs; insulation films and cell structure remained fully intact

Modular System Architecture Enhances Thermal Safety

SigenStack’s performance under extreme conditions is the result of a safety-first philosophy embedded in its design from the ground up. The system’s modular architecture and compact stacked structure naturally suppress the escalation of heat and flame, starting with the pack configuration itself.

Each battery pack contains only 12 cells—far fewer than the 52 or 104 cells typically found in 50–100 kWh modules—greatly limiting heat release and flammable gas accumulation during failure. This significantly reduces the risk of thermal propagation or fire spread, while the modular structure provides natural ventilation paths that help prevent gas build-up and overheating.

By contrast, traditional cabinet or containerized solutions, with their closed structure and tightly packed layouts, are prone to heat accumulation and gas entrapment, making flame propagation more likely during thermal runaway.

To further block heat transfer, SigenStack introduces:

• Dedicated insulation layers between cells
• High-performance thermal barriers on pack exteriors, especially where neighboring racks are most exposed to direct flame
  
  

These materials physically interrupt the heat transfer path, even under sustained flame exposure, ensuring that localized ignition does not trigger a chain reaction.

Six-Layer Safety Mechanism Prevents Thermal Runaway

Unlike passive safety models that react to visible flames, SigenStack adopts a proactive, multi-layered safety strategy—intervening at every stage of thermal runaway. The system integrates six distinct levels of defense, including:

Comprehensive Temperature Sensing

Each pack houses 8 sensors across 12 cells, offering far higher coverage density than typical configurations (8–12 sensors across 52–60 cells). This improves thermal anomaly detection and allows early-stage warnings.

Built-in Smoke Detectors

Integrated directly inside the packs, these detectors offer zero-latency response. Compared to conventional setups, SigenStack’s system improves smoke detection response time by up to 60 seconds.

High-Temperature Thermal Pads

These flame-retardant, heat-insulating pads effectively prevent heat transfer between cells and provide additional electrical insulation for system safety.

Insulating Thermal Layers

With resistance over 500 MΩ, these pads reduce short-circuit risks caused by thermal expansion while blocking heat conduction to structural components.

Pressure Relief Valves

Designed to vent combustible gases during thermal runaway, these valves prevent pressure buildup and explosion. For this test, valves were intentionally removed to allow oxygen ingress and create a high-risk fire scenario, simulating worst-case conditions.

Built-in Fire Suppression Modules

Normally, these would extinguish flames upon initial ignition. Their removal in this test further demonstrates the system’s structural capacity to contain fires without active suppression.

Cloud-Based BMS Enables Predictive Risk Management

Beyond physical safeguards, SigenStack is equipped with a cloud-native Battery Management System (BMS) that offers real-time monitoring and predictive analysis at the cell level. The platform delivers early warnings based on evolving trends, supports remote diagnostics and automated inspections, and significantly improves operational efficiency and energy safety across the system’s lifecycle.

Extreme-Scenario Testing Confirms Structural Integrity

“True safety isn't about isolated specs—it's about being prepared for the worst in every detail,” said the lead engineer of Sigenergy’s testing team. “This full-scale fire test represents the ultimate validation of SigenStack’s system-level safety design.”

The success of the test highlights SigenStack’s ability not just to resist ignition, but to isolate and contain fires even in the absence of active intervention, proving its readiness for real-world deployment under demanding conditions.