Most (if not all) bluetooth low energy devices include battery level in the information they broadcast.
It would be pretty handy if Zwift could check and report the battery level on paired devices and, when the battery is low, send a warning to the screen.
“Warning! The battery level on your (heart rate monitor | cadence sensor | power meter) is 10%. Consider changing the battery soon.”
I’ve noticed that my Garmin lights, that connect using ANT+, will report power levels to my Edge 1030 … but none of my other ANT+ devices do (mostly Wahoo).
It’s possible that the Wahoo devices aren’t reporting power over ANT+ or that Garmin has created a private extension to ANT+ that included power data.