Enduro 3 Battery Thoughts?

1-2 hours of training without music will drain about 1 day of battery time. Adding music to that will really drain the battery. If you look at the battery information you will see that GPS All Satellite Systems will get your 80 hours of use. If you add music to that you will only get 22 hours. So, music is a battery hog.

If you are bringing your phone on your runs you can play music from it. I never play music on my Enduro since I always bring my phone. I don't like to prepare my music or pods and I want to be able to switch between them however I like. The watch can still control the music on the phone.

Pulse Ox uses a lot of battery. Do you think those values are useful? They are not used for any other metrics.

CIQ apps might or might not use a lot of battery. Hard to tell. 

On the mobile app (if you have Android), can you go to Settings > Notifications > App Notifications and just have your messaging apps checked. (eg. only check & receive notification alerts on your watch from Messenger, FB Messenger, Gmail, Outlook, etc.) That way it's not polling for every app's notifications- just relevant messaging ones.

I don't know if it would help.

I really don't see anything wrong with the things you have set up. Regardless, I would mainly be concerned with the suggestions Garmin themselves suggest in the manual:

My choices that I do or don't ignore and get the est. battery life @ 36 days:

Change the power mode during an activity.
Power mode things are so convoluted. I've never touched this.

Turn on the battery saver feature from the controls menu.
I've never touched this. See above

Reduce the screen timeout.
I have it set to 4 or 8 seconds. Whatever is short.

Reduce the screen brightness.
It's like at 20%

Use UltraTrac satellite mode for your activity.
I just use the stock settings for every activity.

Turn off Bluetooth® technology when you are not using connected features.
Mine's on all the time.

When pausing your activity for a longer period of time, use the Resume Later option.
I do this sometimes but I'm also not running all day, every day. As long as I stop activities when I'm done with them, having the watch poll for location while I'm taking a 5 minute rest break while running isn't a big deal.

Use a watch face that is not updated every second.For example, use a watch face without a second hand.
I prefer the stock portal-style watch face, but any face that doesn't tick off seconds should be fine I would think.

Limit the phone notifications the watch displays.
I personally don't want to receive phone notifications on my watch - or on my phone for that matter.
Mine are disabled on the watch settings > connectivity > phone > Notifications > status off
Otherwise, the above thing I wrote out to limit which apps on your phone will push to the device may help
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Stop broadcasting heart rate data to paired devices
I don't broadcast. I receive heart rate from a chest strap. Broadcasting from watch to other devices is rare because you'd have to have some specific fitness equipment that can receive it.

Turn off wrist-based heart rate monitoring
NOTE: Wrist-based heart rate monitoring is used to calculate vigorous intensity minutes and calories burned.
Mine's on 24/7. Turning it off would kill half of the fitness features.

Turn on manual pulse oximeter readings
I've tried 24/7 and only during sleep but it chops off days of battery. Unless something is really wrong with you, you'll always be breathing normally. I don't think Garmin uses continuous Pulse Ox monitoring for any fitness formulas anyways.

I use my phone for music so I have no idea what the power drain is on the watch. All of the Garmin apps are just one more thing to fiddle with rather than just using my phone. I usually run w/ a Camelbak, Spi belt, or some running belt w/ my keys and phone in it so I do media from my phone.

My guess is the combination of the pulse ox @ night and the using all of the music apps is what would chop the battery life so significantly.  If you're using a media app, I wonder how the app handles synching with whatever cloud service it uses.  Say, Spotify or Amazon Music, they probably start up the WiFi on the watch, phone home to that hosting company, tell them what you've just played, receives any new audio files, and then shuts down.  The watch itself could use a percent of battery each time it polls for new media.  And I don't know how often they poll- just when you open that app on your watch?  Every x hours in the background even when you aren't connected to your home WiFi? How long does that process take?  Are the files huge (like an hour long podcast episode) and could fail when downloading a large file and continue retrying.  I don't know.

Never understood music was such a battery hog. Thank you. 

In addition to what others have said, I would suggest turning off every second recording unless you have some special purpose use case like being a race director.  Turn off pulse ox -  I use that 24x7 if I get Covid to see if am getting into a dangerous state - apart from that it stays off.  Suggest against turning off incident detection for your safety.

Thanks for all the suggestions guys!  

In response to some of the suggestions, I don't take my phone on my runs as I like to be free and without any distractions while I'm logging miles.  So music on the watch is important.  I am not really complaining about the 12 to 13 days, just wanted to see if it was in line.  I also turned off all notifications from my phone to the watch.  I don't use it for smart notifications and it mainly syncs to my phone for weather updates and uploading my runs to connect.  In all honesty, I wish they'd let you sync weather and GC via wifi so I can turn it off after a sync.  I also try and leave BT off during the day most of the time as well, but as this is manual sometimes I forget to turn it off and leave it on. 

One thing that is intriguing is the pulse OX and every second data reading.  Most people turn this off for 247 and some people turn it off for sleep.  This metric is not used for training?  Just curious as I don't know. 

I'll need to research a bit more on the 1 second recording vs smart.  

Bluetooth, notifications and 1 second recording probably don't affect the battery that much for anyone to be bothered about. My guess is that you might get a few hours extra, but is it worth that for the hassle of micro managing the device?

My guess is that you wouldn't even notice any difference in battery time if you just keep those on.

Pulse Ox is not used for anything. So, only keep it on if you really need those values.

Using a watch face without data that updates every so often is a good idea. So, showing seconds, HR, steps, weather etc on the watch face is a no no if you want to save battery. All that data is just a swipe away.

Navigation is a huge battery hog if you are viewing the map since it will redraw the screen over and over again.

Interestingly the AMOLED versions don’t seem to suffer from using music. Coming from a F8 47mm AMOLED, it always lasted its 7days with AOD turned on and 3 hours a week of activities with music. 

Fenix 8 AMOLED 47 mm with AOD got up to 7 days in smartwatch mode so also doing 3 hours of training with music is long time over the specification. Are you sure it wasn't the 51 mm model?

According to the specification music got about the same affect on the battery as with the Enduro.

Fenix 8 Battery Information

Yea was pretty consistent for the 6 weeks I had it.  Maybe 6 days but definitely no less.  
I sold it tho and got an Enduro 3.  I like the MIP display better. 

Looks like the watch supports a notion of pulse ox acclimation which I guess might be useful for altitude training.  I have never tried this but since you asked about this I’m pointing it out.