It has happened to me 2 or 3 times that I am about to start training and I see that a sensor is not connecting, its battery is no longer working.
The first time it happened to me I had stopped using it for a couple of weeks, just as the weather became very cold and I sensed that the battery was already low and with this change it died completely and the application did not measure it.
Now I can confirm that it is not. New battery, using my sensors daily or every other day every week (speed, cadence, HRM) and without warning again the HRM does not connect.
I changed the battery and it worked wonders as always.
Until now the Battery Status in Connect was always green and OK without any advice of low battery.