But I recently put in a new battery and have the phone in a Jackery battery case. The update was just installed so time will tell.
HOWEVER I see a lot more features that can cause more battery use. On this phone I am not signed into iCloud or much else. I don't even have it checking mail. I usually get 5 or more days on a charge (thanks to the new battery and Jackery case?)
So you wrote "without doing anything" but here I see a lot more bells and whistles so it may take time to turn them all off.
I have iPhone 6S and I updated to iOS new update 11.3.1. But the problem after installing the update is, it is draining battery quickly.
Like I have a battery about 70% and after 15 minutes it reduced to 25% without doing anything.
Anyone facing same?