I use this app to track the device status [RELEASE] Device Watchdog
After having a few sensors not report for months and not knowing, now this app runs an activity report daily on all battery devices and sends a pushover notification, that you can verify that activity has occurred within the last 24 hours. If one device doesn't report in 24 hours I change the battery. As I have many devices that are either at 1% for months now still working, or devices that have been at 100% for months now and the battery % never changes.
