Various weak-current auxiliary equipment of urban rail transit such as subways and light rails adopts 12V lead-acid batteries as emergency backup power to ensure equipment operation safety. The batteries mainly provide continuous power for carriage emergency lighting, station prompt screens, emergency intercom equipment and signal auxiliary controllers during power outages. The rail transit power supply environment is complex with strict requirements for power stability and safety. 12V lead-acid batteries feature constant voltage output, flame retardancy and stable discharge, which can switch power supply seamlessly during sudden power failures. Their maintenance-free design adapts to long-term continuous operation and reduces operation and maintenance costs effectively.