iPhone 6s here, serial falls within the "range", but apparently there's more affected than that. My phone is a couple months out of warranty. Called Apple before I went to the store and as soon as they took my serial, they had me talk to a supervisor. She was really nice, did some checking and said I needed to take it into the store for replacement ( she couldn't tell me whether phone or battery ). Have an appointment today, taking my laptop to show this thread and the link to this article:
https://www.apple.com/jp/support/iphone6s-unexpectedshutdown/
Mainly so I don't have to go through the battery and phone diagnostics that won't find any issue.
I'll update with status, hoping it gets fixed. Been going on for 2-3 months now at least, glad I found this thread and the article. Yesterday I watched my phone drain from 57% to 14% in a matter of about 15 minutes, with no apps running, I just clicked the home button every couple minutes to check battery. Then I powered off and back on and was at 34%, streamed with slingtv for about 25 minutes, down to 26%, then it shut down on its own, requiring plug-in to be able to power back on.
This is, by far, the worst phone experience I've had, because also since 10.x update, I've had lock ups, network I presume. Where when leaving ( usually Facebook ) if I switch to Safari, the phone locks for about a minute solid, can't power off, kill apps or anything, just have to wait until it comes back. Updated Facebook a couple of times through this, same issues, happens some with other apps. Basically I have to use my phone as little as possible due to these two issues, which is crazy. And with the battery issue, just using the phone for calls/texts can be a crapshoot, as even starting with a full charge ( 100% ), within hours of no use, the thing could be on the verge of shut down. I'd like to see Apple slow down on the iPhone releases for a bit and get their HW and SW quality back to where it once was. ( As I write this on a 6+ year old, ( original ) MacBook Air 11", which still functions fantastically, like it did the day I took it out of the box! ).