UL 9540A

What this standard covers, in our words

A TEST METHOD, not a product standard. UL's own catalogue entry gives that title and lists Edition 6 as active, published and ANSI-approved 13 March 2026. Its scope: the methodology determines the capability of a battery technology to undergo thermal runaway and then evaluates the fire and explosion hazard characteristics of those battery energy storage systems that have demonstrated that capability; the data supports a manufacturer's installation instructions (separation between systems, fire protection) under codes such as NFPA 855. Its subject is stationary energy storage installations, not a vehicle's traction pack. A statement that a product was 'tested to' it, or that its cells were, is a statement about a test run and not a certificate of anything.

This is our summary, not the standard’s own wording — the text itself is published by UL Solutions and it is the document to read before relying on anything here.