Battery Draining Fast after updating to 16.5 version

If the issues you mentioned are indeed caused by iOS, it's likely that numerous users who have upgraded to iOS 16.4.1 (a) are experiencing similar problems. However, in order for the community on this forum to provide helpful responses, it would be beneficial for you to specify the nature of the issue you are encountering. Without this information, it may be difficult for others to address your concern effectively.

Protect & Prolong the life of your iPhone's Battery:

1. About the battery usage on your iPhone, iPad, and iPod touch ...
2. Batteries - Maximising Performance - Apple (IN)
3. iPhone Battery and Performance

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

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Please re-post with detail so that someone else can help.

Same problem. Since installing 16.5 (20F66), iphone 14 pro max has gone from having incredibly good battery life to OK battery life; seems to drain about twice as fast. Even drains noticeably when lying unused in airplane mode. I've made no other changes to the phone.

I have the same problem. My phone drains even when the screen is off. and locked. Just as an example, last night, It went from 50% to 17% in 1.5 hours when I wasn’t using it, and no apps were running It’s been going on for a few weeks and started around the update. I’m having to charge multiple times a day, and now my battery health has dropped as a result. I’ve done all the things suggested to minimize battery use, and it has made no difference. I have an SE less than a year old. It seems others have the same problem. I wish Apple would acknowledge there is an issue and say whether a fix is coming.

I did have this issue too after updating my iPhone 13 to iOS 16.5 and again when using iOS 16.5.1.

One method which really did worked for me is:

1. Create a backup of the iPhone using iTunes on the computer
2. Restore the iPhone firmware (also using iTunes)
3. Allow iTunes to download and reinstall the entire firmware package
4. Restore backed-up iPhone data from #1 above using iTunes

Hope this helps.

My iPhone is losing battery level at an alarming rate. 25 % in less than 2 hours with little use.

Yeah my iPhone 11 all of a a sudden started draining 2x faster after the update so I just started using power banks