Garmin 820 battery issues

My Garmin 820 is exhausting its battery very quickly (generally in 50 miles or so). I’m running the MPA/Power and TTE/TTR Apps. Are they likely to be the source of the problem?

It’s not been reported often. Do you happen to be running any other apps simultaneously? Navigation? Live-track? I often turn my device’s bluetooth off once my signature is updated on the data fields to save battery, as well as keeping the screen brightness low.

No other apps. Brightness low. I haven’t turned off Bluetooth or WiFi. I can try that.