Maybe someone who has this experience could inform us.
I keep meaning to test this scientifically as I have a 41 mile race in a couple of weeks!
I’ve done loads of 2hr runs and a few 3hrs runs where I THINK battery drain is typically around 20 to 30% when running standalone with watch only starting from 100%...sometimes I click the watch into airplane mode before starting (just a habit from another watch, I think there is slightly less drain if it’s not trying to find a phone all the time).
This week did a 3.5hr hilly run but with phone carried as well (since I’ll be doing that on the 41miler) and I think battery was showing 80% at the end (having started at about 98%) (+ about 5% drain on the phone, which is a XR)....so should EASILY be able to run even a very slow marathon.
I use the Workoutdoors app, and looked at the map reasonably regularly on the way out, plus get alerts every 1km and probably glanced a handful of times in between too...(was pretty careful on maintaining close to a target pace for first hour as was running to meet up with a group who were setting off from a given location at a specific time so I could run with them for the middle hour).
Also received about 6 or 7 messages, and replied to two using my voice into the watch and one by pressing a canned response...don’t recall any other notifications.
And, erm, used watch to pay for a little coffee at McDonalds midrun! ♂️
No music. And I think brightness is turned down to minimum. Don’t think I’ve done anything else specific to extend battery life. I leave HRM turned on and intend doing so.
Doing a 20mile run on Saturday but planned to take longer or close to my marathon time (roughly 4hrs)...will charge to 100% beforehand and will either be tethered to phone or will run standalone so gets worst case battery scenario, haven’t decided yet.
41miler will be tethered to phone.
Doing a 48hr race (but only planning running during daylight) in a couple of months but will likely take phone and will be moving 4 to 6hrs max at a time before being able to recharge....should get confidence this is doable or not from the 41 miler...plan is to record each session separately and then glue them all together in Strava.
Edit: AW4, non cellular.