Sunwoda completes large-scale fire test for ‘5 MWh Liquid Cooling ESS’

<p class="p1"><span class="s1">Sunwoda conducted a large-scale fire test of its 5 MWh liquid-cooled energy storage system, showing contained thermal runaway in one unit without fire spreading to adjacent systems under extreme UL 9540A conditions.</span></p><p><strong>From <a href="https://www.ess-news.com/2026/05/08/sunwoda-completes-large-scale-fire-test-for-its-5-mwh-liquid-cooling-ess/" rel="noopener" target="_blank">ESS News</a></strong></p>
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<p>Chinese energy storage manufacturer Sunwoda is the latest to complete a large-scale fire test (LSFT) in the presence of independent observers, having set alight its “5 MWh Liquid Cooling ESS” product.</p>
<p>With the task set to meet relevant international standards such as UL 9540A and CSA C800, Sunwoda said it carried out the test in “a more stringent setup than typical real-world deployment” as it aimed to validate its product.</p>
<p>The test itself was carried out with a configuration of five actual full-scale 5MWh Liquid Cooling ESS systems, including one initiating unit and four target units, with a minimum spacing of 15 cm, far more dense than normal. All were charged to 100%, and active fire suppression systems were disabled. As per requirements, in the initiating unit, explosion vent panels and ventilation panels were opened, and thermal barrier materials removed to fully test thermal runaway propagation.</p>
<p>Sunwoda said the test was carried out in accordance with ANSI/CAN/UL 9540A:2026 Sixth Edition, and CSA/ANSI C800:2025. To ensure a rigorous process and credible results, the test was conducted by CSA Group and reviewed by Atar Fire’s Fire Protection Engineer.</p>
<p><strong>Results</strong></p>
<p>Sunwoda said that during the LSFT, the initiating unit experienced thermal runaway and sustained combustion for over 12 hours, yet the fire remained contained, with no propagation to adjacent units, and structural integrity was maintained throughout.</p>
<p>Sunwoda stated that across cells, packs, and systems, its”multiple protective measures work together to delay heat transfer, reduce thermal impact between adjacent systems, and support the containment of thermal runaway.”</p>
<p>Multiple supplied photos are shown below.</p>
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