This rise in the number of fires involving lithium-ion batteries has escalated the need for a methodology to determine the root cause of the fire, which will be proposed herein for the post-incident assessment. Just as with fire in general, investigators use a systematic framework, reliant on collection and careful analysis of forensic evidence, and based on the scientific method of inquiry. This article presents a systematic methodology or process to analyze batteries involved in a fire during the post-fire analysis. It involves examining Li-ion cells of varying construction, using an approach including visual inspection, X-ray, CT scan, and testing of exemplars to identify operation behaviors contributing to an event. The focus is mainly on the most common designs of consumer Li-ion batteries, cylindrical and pouch. The framework applies both experience from literature and observations from investigating over a thousand battery-involved fire incidents.
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