I have the same issue week after week since I bought the watch in 2018. I charge my fenix5 to 100% and after a day or two, the HR sensor stops working. For some reason this causes the battery life of the fenix5 to drop from about 80% to 40%. When I restart the watch, the HR sensor seems to be working fine and the battery shows +- 80% again.
It has happened before where I didn't notice the sensor stopped working and the battery drained completely due to the HR sensor not working.
Please help
