Odd, I just finished a night shift in which I used my Galaxy S9 quite a lot, after a day of using it quite a lot (including wifi hotspot, camera, video, maps & navigation) and it's showing 65% battery. This is after 23 hours of constant usage. I think this may be due to both better and larger batteries in all flagship phones, as well as better power management in both Android and iOS. Or maybe I just got lucky?

I have an S8 and generally have to charge it half way through the day. Going on a 1 1/2 walk while just listening to spotify will drain the battery between 18-24%. Been trying to decide between the Pixel, XR, or S9 since its been so bad recently. If the S9 really has that amount of improvement I wouldn't mind doing the straight upgrade since video/picture quality isn't a big deal for me.

Sounds like I got lucky. I've noticed this with Li-Ion batteries; some are awesome and provide days of charge, and some are terrible and require half-daily top-ups. I'm not sure if the manufacturers do testing to determine which ones are better.

Spotify seems to be a real battery hog, but are you in a low-signal area? (especially on LTE). I've noticed a big difference in battery life on the S8+ (and to some extent, the Note 9) based on whether I'm in a "1 bar" area or "4 bar" area.

That might be it. I'll give it a check later today but I am walking out to the trail. I'd have hoped since I have the playlists downloaded that it wouldn't matter.

Sorry - the two issues are separate.

* Spotify is inefficient (wonder how much is DRM?)

* Low signal causes your phone to increase transmit power.