One of the most important features of modern, computerized, radios is that you can make them talk to you. After all, with setup telemetry link from UAV, radio should “know” things. Things like battery voltage for example. Why not make FrSky Taranis (or Horus or Taranis X Q7) talk to you and report LiPo voltage in a smart way?
In OpenTX menu navigate to last page called Telemetry and check if VFAS is reporting proper value.