As battery technologies continue to advance, batteries are being placed in an increasing number of consumer products and being used for energy storage applications from microelectronics to the grid scale. Because of the high energy density in a battery, the sudden, unintended release of stored energy can have significant negative consequences. Consumer products are often in close proximity—and are even sometimes attached—to people, and large energy storage systems may be supporting critical infrastructure. Manufacturing variation (both within one supplier’s processes and between different suppliers producing “identical” batteries / cells) can lead to variations in the conditions under which the onset of thermal runaway occurs as well as the differences in the resultant evolved gases. In this study, we subject lithium-ion cells produced by different commercial manufacturers to the same abuse conditions via external heating in both adiabatic (accelerating rate calorimetry or ARC) and non-adiabatic conditions. We examine the behavior of the cells during these abuse conditions, and analyze the volume and composition of the gases evolved due to thermal runaway in order to investigate potential differences in severity and/or mitigation strategies. Additionally, the potential effects of inert atmosphere on the failure severity will be evaluated. The general implications of this work as it relates to assessing hazards and designing for safety will be discussed.