I have been using the Garmin edge 810 for several years, and have not noticed the battery charge live to be less than 8 hours when fully charged.
Recently, I purchased the Varia RTL510 rear light/radar that works well w/o any problems. However, I had to increase my screen light all the way so I could reliably see that oncoming cars in the display during bright sunlight. Then I noticed that the fully charged Edge 810 didn't last more than 4.5 hours.
Is the charge being drained because of the Varia, the increased brightness of the display or reduced battery life? Battery life when new is supposed to be about 15 hrs. Would that included the screen set at max lighting?
Any info is appreciated.