<p>Thermal runaway (TR) of lithium-ion batteries caused by electrical, thermal, and mechanical abuse is a primary contributor to electric vehicle (EV) fires. To address the unclear propagation mechanisms and hazard characteristics of thermal runaway fires in full-scale EV battery packs, a comprehensive thermal runaway fire test on battery pack was conducted in this study. The experimental results revealed that TR propagated from individual cells to adjacent cells, ultimately engulfing the entire pack. The combustion dynamics of battery packs differed significantly from those of individual cells, exhibiting rapid fire escalation and complex combustion-explosion behaviors. A thermal radiation prediction model was established based on experimental data, according to the thermal radiation prediction model, the thermal radiation intensity of the battery pack at different distances can be obtained, so that the safe distance between various types of equipment and the electric vehicle can be determined, providing critical insights for designing safety distances and suppressing TR propagation in battery systems of EV.</p>