I know people with SE and 7. All of them have new batteries or new phones. They get 3-4 hrs max.
Can you post a screenshot?
Yes, attached.
This is not a full 100% to 0% test because that would take ages, but a 100% to 75% test which should be somewhat reliable since the battery is in a good condition. Before replacement the battery didn’t deplete linearly at all.
Anyway: I took my iPhone 6s off the charger at 7:30PM in the evening, 100% charge. Battery condition 97%.
I used actively various apps until the battery was down to 75%. Safari, Twitter, Maps, took 25 photos, used news apps, downloaded couple of updates from AppStore, read mail, browsed photos, watched YouTube for 13 minutes, no headphones of any kind.
Screen was set to automatic brightness, indoors, normal living room lightning. The phone was connected to 5GHz WiFi and 4G networks (2/4 bars; I took the case off for a minute and got 3/4 bars). Cellular data was off because my second backup SIM does not have unlimited data and I couldn’t be bothered to remove SIM from my other iPhone.
The result:
1 hour 36 minutes screen on time with 75% of battery left.
(I find Mail app’s share of battery use strangely high, I did read e-mails and wrote some, but didn’t except that. Is it polling the server all the time when the app is in the foreground or what...)
If we assume that the battery depletes somewhat linearly I would get about six hours of this kind of use. Way more than 3-4 hours. Of course if you keep the phone on the table for days and start using it when there is 10% left you will not get even an hour.
If I set the brightness to max, play some games, heavy 4G use, shoot lots of 4K videos, then we are talking about 3-4 hours probably.
I don’t think there was much of a difference with earlier iOS versions. Maybe 6-7 hours, although battery stats display was quite different then. I do remember that the original battery went bad disappointingly quickly though.
An iPhone 6s Plus with a good official battery should generally last longer which was the claim I found unbelievable.
Poor third party battery, use with max brightness, gaming, poor network conditions. All those things affect battery life.