DLFPV&reg; Lipo Battery Low Voltage Tester Checker 1S-8S Buzzer Alarm with LED Indicator for RC Helicopter Easy to use - works with any 1-8S Lipo/Li-Ion/LiMn/Li-Fe RC drone battery Just plug into the balance plug and the LED will cycle through the individual cell voltages as well as list the total voltage You can set the alarm from 2.7 to 3.8V per cell or you can turn the alarm off Super loud alarm sound makes it easier to find your drone Protect the battery from overcharging and overdischarging