Interesting observation these last few days
My WS80 has started to flag low voltage during the cold nights these last few days.
This is not unexpected since the Lithium cells have been in place since Aug 2019 though I was hoping to scrape through to March for a spring refresh of my external sensor batteries.
What's interesting is that the Ultrasonic component needs good minimum voltage while the rest of the sensors in the array operated OK and the overall sensor data was transmitted consistently.
What you see is the wind speed and direction just freeze at the last value and repeat until enough voltage returns or sunshine arrives!
For me this seems to be around 2.75V that the ultrasonic component stopped working (I have alerts setup on Ecowitt.net that send me the voltage values)
So I guess the lesson learned here is that in order to keep wind readings going I would recommend annual battery changes for the WS80 unless you live in more equatorial regions or have higher sunshine averages and set a threshold of 2.8V!
