Numerous threads on this forum about Xs-Max battery life but I hadn't found one on regular Xs battery life so thanks for posting one. I was just about to start a thread on this myself because yes, I'm having very crappy battery life on my new Xs.
I upgraded from the 6s I bought on release day in 2015 so it's got a pretty much exactly 3 year old battery in it and my 5-day-old Xs is giving me worse battery life than my 3-year-old 6s is. I just did a check 30 minutes ago after I'd left it off the charger overnight. My Xs dropped 5% battery, my 6s would drop more like 2% in that scenario.
Yesterday I went out with 78% battery. I was out for about 3.5 hours during which time I sent/received 3 SMS messages, made no phone calls, used Google Maps twice for about 60 seconds each time, hailed an Uber (location services set to only use when app is active), and did 2 NFC electronic payments. I have no email set up on my phone, no iCloud syncing active and my calendar and contacts are set to manual pull only and I didn't do any manual pulls. The only other thing I did was 1 hour and 27 minutes (minus however long the Uber/maps/texting took from that screen time total) of iBooks reading but that is deliberately with the iBooks theme set to dark (white text on pure black background) to optimise power consumption for an OLED display and in terms of the number of pixels lit on the screen is probably not far off the number that Samsung lights up with its always-on-display, i.e. the screen was effectively more off than on so definitely nothing like watching a video or surfing the web.
Well, all that activity left me with 52% battery when I got home - virtually no demanding activity dropped 26% off my battery life! On that basis this phone is going to give me about 6 hours of super-battery-optimised white-on-black iBook reading before it dies. How on earth does that tally with a phone that Apple claims gives 14 hours of wireless video playback on a single charge (
https://www.apple.com/uk/iphone-xs/specs/ )
I'm not happy to the extent of considering returning it, going back to my 6s for a year, and waiting to see if 2019 might finally be the year when Apple can deliver good battery life.
There's been lots of talk about WiFi and mobile connectivity issues on the Xs and Xs-Max and I do seem to get worse signal strength as shown by the indicators on both WiFi and mobile when I'm at home compared to my 6s. Perhaps this is an issue with simple standby and keeping connected to the phone masts draining a lot more power in less-than-perfect reception areas. If yes then, with a lot of other chatter about how the new Intel modem in the Xs is a step back technically from the Qualcomm one in the X, I wonder if this is fixable in software. Do I wait long enough to find out?
Ultimately I'm going to play for another week, maybe do a few marathon reading sessions to see how much iBooks time I can get per 10% of battery loss. Leave it in airplane mode for a day to see how much battery is lost then, and perhaps some other experiments like playing music on a loop for 12 hours or so to see how the music playing time compares with Apple's claim (Apple claims 60 hours wireless so I would expect at least that when playing local content).
I don't want to end up returning my Xs because I like the new screen, FaceID and the general form factor but if battery life is this disappointing then I don't think that Apple deserves my money with this year's model.