The emerging use of rechargeable batteries in electric and hybrid electric
vehicles and distributed energy systems, and accidental fires involving
batteries, has heightened the need for a methodology to determine the root cause
of the fire. When a fire involving batteries takes place, investigators and
engineers need to ascertain the role of batteries in that fire. Just as with
fire in general, investigators need a framework for determining the role that is
systematic, reliant on collection and careful analysis of forensic evidence, and
based on the scientific method of inquiry. This article presents a systematic
scientific process to analyze batteries that have been involved in a fire. It
involves examining Li-ion cells of varying construction, using a systematic
process that includes visual inspection, x-ray, CT scan, and possibly elemental
analysis and testing of exemplars. For the purposes of this article, we are
mainly concentrating on the most common designs of consumer lithium-ion
batteries, cylindrical and pouch. The methodology applies both scientific
literature and observations gathered while investigating over a thousand
incidents.
