FrSky Battery Voltage Sensor - FrSky Telemetry System
This sensor is used to collect in-flight information about your onboard LiPo battery via a telemetry-enabled receiver to a telemetry-compatible transmitter module where it can be displayed on an LCD screen or via a transmitters speaker using voice.
The sensor is pre-set up to take 0-19.8v readings for up 5s batteries. However, It will work with 1s, 2s, 3s and 4s batteries too - but will become more accurate if you decide to set it up for lower voltages only. To do this, you can unsolder and resolder one of the wires to the correct pad. Note that additional replacement heatshrink is included in order to reshrink the sensor afterwards.
Features: Three voltage ranges: 0V~6.6V (1S), 0V~13.2V (up to 3S), 0V~19.8V (up to 5S). The battery voltage division ratio for each option is 2:1 (1S), 4:1 (up to 3S), 6:1 (up to 5S).