Abstract: In order to ensure the safety and reliability of underground power supply in coal mines, prolong the service life of batteries, and reduce the inconvenience and the waste caused by replacing batteries, it is proposed to apply the lithium iron phosphate battery with floating charge protection to the underground coal mine as an emergency power supply for refuge chamber and rescue capsule. Then, a measure to ensure the safety of the battery is proposed to ensure the safety performance of the battery by using the battery self-balancing and the battery management equilibrium system. Finally, the capacity fading characteristics of the battery in floating charging state are analyzed, and the floating life cycle of the battery is predicted through the existing analysis data. The analysis results show that the floating charge protective lithium iron phosphate battery can effectively prolong the floating life of the standby battery.