Abstract: Lithium iron phosphate battery is prone to thermal runaway when it fails, producing lots of combustible gas and causing fire and explosion. The use of sensors to monitor the thermal runaway of batteries is an effective means to avoid the spread of energy storage battery accidents. Therefore, five kinds of multi-in-one composite sensors with different detection principles were made by ourselves. The detection parameters included the volume fractions of H₂, CO, CO₂, and volatile organic compounds (VOC), the smoke mass fraction, and the pressure and temperature in the cabin. In a 40-foot real energy storage chamber, experiments on thermal runaway monitoring of batteries at different locations were carried out, and the effects of ignition on thermal runaway detection were compared. The research results show that H₂ sensor based on catalytic combustion principle can detect H₂ faster than that based on electrochemical principle, and VOC sensor based on photo ion principle can detect VOC faster than that based on electrochemical principle. VOC is detected earlier than H₂ and CO. On the one hand, the electrolyte leakage volatilization is earlier than the generation of H₂, on the other hand, because the blue film of the battery is heated to produce a part of VOC, H₂ is detected slightly earlier than CO and smoke. In the case of non-ignition, the air pressure and roof temperature are not suitable for detecting the thermal runaway of the battery. In the case of ignition, the concentrations of CO, smoke and CO₂ increase, while the concentrations of H₂ and VOC decrease to varying degrees, and the temperature in the cabin increases rapidly. Based on the experiment of battery thermal runaway detection, the proposed strategies, threshold range and detector spacing of battery thermal runaway and fire detection in lithium iron phosphate battery storage compartment are presented.