This white paper explains AEGIS Loss Control's viewpoint on the present status of battery storage systems and is intended to serve as a reference tool for AEGIS members interested in Lithium-ion Battery Energy Storage System (Li-ion BESS) facilities. Lessons gathered from Li-ion BESS occurrences, full-scale fire tests, and changes in regulations and standards will be utilised to update this paper on a regular basis as technology, fire testing methodologies, and mitigation strategies evolve.