Bumping an old thread rather than creating a new one. I have an Edge 520 Plus (slightly different model, I know). I use the head unit on multiple bikes, I always use a heart rate strap and a speed sensor, two of my bikes have power meters.

How long should I expect to get out of the battery? Lots of threads online about short battery life with these units, but wanted to get a consensus.

I'm getting 4ish hours on cold days, up to 7-8 hours on warm days. The advertised 15 hour seems unlikely in any sort of normal use case. I'm using the latest firmware, which is 5.70. I run 0% brightness but nothing else turned off. This has been a rock solid headunit, I really like it... but the short battery life is a bit irritating.

Like some people above with the 520, I had mine die on me in the middle of a ride a few month ago... but then continue to track me for hours and upload perfectly at the end of the ride. This made me think at the time that the battery life indicator was likely inaccurate. I think whatever Gremlin infected the 520 also spread to the 520 Plus.

An important thing to note, on any Garmin, is that the fastest way to run down the battery is to have the map screen (or any other full screen graphical display, if you are using custom apps/widgets) on all the time. One of the best ways to conserve battery is to just have the main page show minimal statistics (e.g. power, speed, cadence, distance, heart rate) - have everything else on separate pages that you can refer to from time to time.