UL 9540A Commercial Energy Storage Systems (ESS) Testing
Your Test Plan for Safe Commercial Battery Energy Storage Systems
Ensure your products and systems meet UL 9540A requirements
The use of battery energy storage systems (ESS) in commercial buildings is growing rapidly worldwide. For lithium-ion battery and ESS manufacturers, ensuring the safety of these products and systems is crucial, not just for everyday operation but also under demanding conditions and during catastrophic events. Understanding and mitigating fire hazards, thermal runaway, and other risks associated with energy storage systems helps protect public safety and prevent costly accidents.
UL 9540A is a test method for evaluating the fire safety hazards associated with propagating thermal runaway within battery systems. Thermal runaway happens when a battery cell short circuits and begins to heat up uncontrollably, which can lead to a fire. It’s one of the primary risks related to lithium-ion batteries, which continue to grow in popularity across various industries and applications.
The UL 9540A tests establish that a storage technology is capable of reaching thermal runaway and then assess the technology's fire and explosion hazards.
Benefits of UL 9540A Energy Storage Systems Testing
- Identify and manage potential hazards in energy storage systems
- Ensure regulatory compliance as specified in NFPA 855, UL 9540, the International Fire Code (IFC) and building codes
- Increase safety with comprehensive thermal runaway analysis
- Build stakeholder trust with verified battery performance data
- Enhance brand reputation by adhering to rigorous safety standards
UL 9540A & Thermal Runaway Testing at a Glance
UL 9540A tests determine whether a battery storage technology can reach thermal runaway and then assess the resulting fire and explosion hazards.
Thermal runaway occurs when a chemical reaction spirals out of control and can no longer safely dissipate excess heat. This condition can be triggered by internal short-circuits, overcharging, physical damage to cells, or extreme temperature environments.
The UL 9540A test method is comprised of four levels:
1. Cell-Level Tests
2. Module-Level Tests
3. Unit-Level Tests
4. Installation-Level Tests
If an ESS technology meets the performance criteria at any of the first three levels, further testing is not required. Otherwise, testing continues to the next level.
DEKRA provides Cell-Level Testing, which includes Thermal Runaway Testing, Gas Characterization Testing and Flammability Testing.
Process of UL 9540A Cell Level Testing
Cell level tests force an individual battery cell into thermal runaway in a pressure vessel. Generated gasses are collected and analyzed for composition. These gasses are then used for lower flammability limit (LFL) tests, maximum explosion pressure (Pmax) tests, and burning velocity tests.
Thermal runaway in Energy Storage Systems (ESS) occurs due to the failure of individual cells within the system. When these cells experience an internal short circuit, they release a significant amount of energy and flammable gases. The internal short circuit happens when the cell's internal separator is damaged, allowing for a rapid discharge and a sudden increase in heat generation. This cell-level failure can spread, ultimately leading to the failure of the entire ESS. Internal short circuits are most commonly caused by thermal abuse, physical abuse, electrical abuse or manufacturing defect.
DEKRA specializes in assessing the effects of thermal, physical, and electrical abuse on batteries. In thermal abuse tests, batteries are heated until internal separators fail, causing catastrophic cell failure. This test provides data on decomposition onset temperature and gas generation. We also perform flammable gas testing under UL9540A. For physical abuse, we induce internal short circuits through nail penetration or crushing, collecting data on cell decomposition. Electrical abuse tests involve incorrect charging, external short circuits, or over/undercharging, with data collected on thermal runaway initiation and progression.
Testing can be conducted with or without a pressure vessel. Testing outside of a pressure vessel means pressure data cannot be collected, but it does allow for video of the thermal runaway to be taken. During testing, multiple thermocouples are attached to the battery. This allows for accurate tracking of battery temperature at multiple points on the battery.
Sectors Requiring Li-ion Battery Safety Testing
A number of critical industries rely on Li-ion Battery Testing to ensure the safety and performance. This testing is crucial for mitigating risks associated with thermal runaway and enhancing overall safety in diverse applications.
| Energy Storage Systems | Electric Vehicles (EV) | Renewable Energy |
| Telecommunications | Grid Infrastructure | Industrial Applications |
| Medical Devices | Consumer Electronics | Aerospace and Defense |
Your Experienced Partner for UL 9540A ESS Testing
- DEKRA is an ISO 17025 accredited laboratory, demonstrating its compliance with the international standard
- Offering state-of-the-art labs and testing facilities to perform ESS testing worldwide
- A leader in the future of mobility and EV testing
Did you know DEKRA can perform all three required UL 9540A Cell Level Tests?
DEKRA is one of only a few labs in the US certified and equipped to conduct all three UL 9540A cell-level tests, meeting the increasing demand for this critical assessment.
UL 9540A testing is a standardized test method used to evaluate thermal runaway fire propagation in battery energy storage systems (ESS). It helps characterize the fire and explosion hazards associated with lithium-ion batteries and other battery technologies.
UL 9540A battery testing helps manufacturers understand how battery systems behave during thermal runaway events. The resulting data can support safer product designs, code compliance, installation planning, and fire protection decisions for battery energy storage systems.
Thermal runaway occurs when a battery cell generates heat faster than it can dissipate it, causing an uncontrolled increase in temperature. Thermal runaway testing helps evaluate behavior that may lead to fire, gas generation, or explosion hazards if not properly managed.
Battery off-gas characterization measures and analyzes gases released during thermal runaway. The resulting data helps evaluate flammability, explosion hazards, and potential fire protection requirements for battery energy storage systems.
UL 9540A testing is commonly performed on lithium-ion battery technologies used in commercial energy storage systems, renewable energy projects, utilities, grid infrastructure, and other stationary battery applications. UL 9540A cell-level testing can help characterize thermal runaway behavior at the battery cell level.
UL 9540A test data is commonly used to support compliance with NFPA 855, the International Fire Code (IFC), UL 9540, and other codes and standards governing battery energy storage system installations. The data can inform engineering analyses, fire protection decisions, and installation planning.
ESS battery testing is widely used by battery manufacturers, energy storage system developers, utilities, renewable energy companies, electrical equipment manufacturers, engineering firms, and system integrators developing battery energy storage systems.
After UL 9540A testing is completed, organizations receive technical data related to thermal runaway behavior, gas generation, flammability, and fire hazards. This information can support product development, engineering analyses, code compliance, fire protection decisions, and installation planning.
An independent UL 9540A testing laboratory provides specialized equipment, recognized test methods, accredited testing capabilities, and objective data. These capabilities can support product safety, regulatory acceptance, engineering evaluations, and customer confidence.
General battery testing evaluates characteristics such as performance, reliability, transportation, or electrical behavior. UL 9540A battery testing specifically evaluates thermal runaway fire propagation, gas generation, and associated fire and explosion hazards in battery energy storage systems.
