FrSky Battery Voltage Sensor FBVS-01 gives live BATT monitoring for Rx with Two Way Telemetry ; suits LiPos from 3v-> or 4s or upto 19.8v (5S) . There are three voltage ranges to choose: 1S lipo for battery voltage range from 0V~6.6V, up to 3S lipo for 0V~13.2V and up to 5S lipo for 0V~19.8V. Please check the battery voltage division ratio for each option below: As supplied works well for 4S or 3S. Requires soldering to Andromeda outer ring ; or DIY solder to pins(not included) for the LiPo balance tab as shown here below with FrSky X4R A2 port connected to the FBVS-01 and the 3S LiPo Pins - the A2 voltage is then activated in the Taranis telemetry section and a Play Value assigned to a switch, then go to Telemetry page and calibrate the voltage (you need a DMM to first see the current voltage of the battery).
The FBVS-01 is typically combined with a D4R-II and a BARO Variometer to give live altitude data. The D4R-II from FrSky (sold separately) is a favourite Rx for C-PPM enabled mini Quad controllers like our Aussie PARIS v2 Hero. and HERO•32 bit naze becuase it is compact, has 1 wire 8 channels ; and can easily be connected to the voltage sensor FBVS-01 and the Variometer SPort with our D4R-II hack below (without any HUB needed!)