The Efficiency of Heptafluoropropane Fire Extinguishing Agent on Suppressing the Lithium Titanate Battery Fire

To investigate the efficiency of heptafluoropropane fire extinguishing agent on suppressing the lithium titanate battery fire, an experimental system was designed and built to perform the extinguishing test. The lithium titanate battery (50 Ah, 2.3 V) with diameter of 66 mm and length of 260 mm was used. A 5 kW electric heater was set under the battery to trigger the thermal runaway of the battery. When the battery fire occurs, the heptafluoropropane was immediately discharged by opening the agent storage tank till to the fire was extinguished. The battery temperatures, ignition time, release time of the agent, time to extinguish the fire, battery mass loss, amount of used agent and mean discharge rate of agent were obtained and analysed. The results illustrate that the single cell or small-scale battery pack fire can be extinguished by heptafluoropropane in the tests. Therefore, heptafluoropropane is a fire extinguishing agent candidate to put down the lithium titanate battery fire. However, due to the violent reactions still ongoing inner the cell and flammable gases ejecting continuously from the cell, the battery may be reignited after it is put down. So it was suggested that the heptafluoropropane agent should be applied as early as possible and with longer spray time than the usual case to avoid the reignition.