Garmin edge 820 - Battery draining very quickly

I am using the Garmin edge 820 as my head unit. I only have my power and heart rate sensor connected to it. I also selected the GPS mode instead of the GPS + GLONASS mode, and set the display brightness to 10%.

Starting at 100% battery level, the battery life drops to ~40% after a 3 hour ride. What can I do to maximize the battery life without shutting down the display?


Following with interest as this subject came up on today’s ride as my friend is having the same problem with his 820.


On this year’s first long ride (4h+) my 820 got into power saving at 3.5h. I didn’t expect that. Now I just bring a power bank taped to the top tube on my longer rides.