Your iPhone’s Battery Might Not Last as Long
Unfortunately, for people who are always on the go, your iPhone’s battery might suffer with iOS 17, especially with older devices.
Many people have reported that their iPhone’s battery lives don’t last as long as before the update. If that’s happening to you, the first thing you should do is simply wait a few days to see if it gets better; every major iOS update kicks off some background optimizations and reindexing that can result in an initial hit on battery life until things calm down.
However, if you’re still having this problem after a week or so, the only complete fix is to hope that Apple corrects this issue with a future software update. If you have an older iPhone, this could also be a sign that your battery is simply getting old. A quick trip into Settings > Battery > Battery Health & Charging will show its status; if that number is lower than 80% or other errors show up here, then it’s probably time to get a battery replacement.
There are also some ways to save battery, like disabling Background App Refresh by going to Settings > General > Background App Refresh or by turning on Low Power Mode which can also be found in Settings > Battery.