NTC inside charger, Fan start working automatically when charger temperature reach 40℃Specification:Model: UY240 Dimensions: 170x90x50mm Battery type: Li-ion battery Working power: 90-110Vac, 50 ~ 60Hz Suitable for Battery Voltage: 50V/51.8/52V Output voltage: 58.8V (For 14S Li-ion Battery) Output current: 4A battery Protection: SCP,OVP,OCP,OTP Charging mode: constant current - Constant Voltage - trickle (floating charge) three-stage intelligent charging Charging efficiency: ≥85% (full load) Working temperature: -5 ℃ ~ +40 ℃ Storage temperature: -40 ℃ ~ +70 ℃ AC power cord, DC connector can be customized. Operating Instruction1. Before charging, please connect the DC terminal to battery first, and then connect the AC terminal.2. After charging complete, unplug the AC terminal firstly, and then unplug the DC terminal.3. No charging or after charging complete, be sure to unplug the DC terminal and AC terminal.LED Indicator:LED 1 red: Power on.LED 2 red: Battery being charged.LED 2 Flash: Battery will be charged completely soon.LED 2 green: Battery has been charged completely.Package:1* 58.8V 4A charger1* US standard power cable1* Operating manual1* Female connector2* Fuse for replacing