I have seen many complaints about the battery life on the 820, but my concern is that the battery life on my 820 is very inconsistent. It is never as good as advertised, but I assume the 11 hour life is with the screen off, no sensors, and gps off while riding indoors. This is not how I use my devices.
I rode 60 miles while using navigation with the screen in the sleep mode, or as I call it the "asleep at the wheel mode" because it often forgets to notify me that I am supposed to turn. I would like to be able to see my speed, cadence, and elapsed time, but I have to chose between navigation or seeing the screen in order to get a full ride out of the 820. This ride was about 5:15 long and I finished with my battery at 60%. I was impressed with the battery life, but don't trust this device enough to attempt a ride this long with the screen on.
One week later (last weekend) I rode the same route in the opposite direction. 2.5 hours into the ride I get a message stating that my battery is low. It was at 100% when I started. This is not the first time that I have had such short battery life. Also during this ride I was getting the turn in 0.1 mile prompt about 100 yards before a turn. After each turn the prompt would remain on the screen for miles. The only way to get the screen to go to sleep was to stop, remove my glove, and touch the prompt to dismiss it.
Are other users having sporadic battery life like this? Has anyone else seen this problem with messages not going away? Is there a comparable edge device with better battery life that will allow me to ride with my screen on?
FYI: software is 10.0.0. I bought this unit shortly after it was released, so I have had it for a couple of years.