This paper discusses multiple safety layers at the cell, module, and rack levels to elucidate the mechanisms of battery thermal runaway and BESS failures. Battery Energy Storage Systems, or BESS, help stabilize electrical grids by providing steady power flow despite fluctuations from inconsistent generation of renewable energy sources and other disruptions. While BESS technology is designed to bolster grid reliability, lithium battery fires at some. This incident was likely caused by leaking electrolyte fluid contacting a conductive metal cabinet frame in the UPS battery room. There were no injuries caused as a result of this incident. However, containing the fire, albeit relatively small, presented challenges. Apart from Li-ion battery chemistry, there are several potential chemistries that can be used for stationary grid. It is common knowledge that lead-acid batteries release hydrogen gas that can be potentially explosive.