Extreme Battery Drain After iOS 18.3.1 Update on iPhone 12

Well, if it’s in the code, try updating to iOS 18.4 that was released just 3 hours ago.

Have you looked at your Battery Usage by App and Activity by App for last 24 hours and last 10 days? That will show what the culprit is. You may have a corrupt 3rd party app causing the majority (all?) your issues.

iphone > Settings > Battery > ignore graphs for now. Please look at the apps and four different views 24 hour vs. 10 day and Battery Usage vs. Activity > look for unusual consumption and app usage per app

Im not saying it is or isn’t an Apple issue, but without the above perspective app(s) can’t be ruled out.

Hard reboot seemed helped me. The one where you need to press physical buttons.

Here the link Force restart iPhone – Apple Support (UK)

MooMooFutch wrote:

It’s showing 85% but like I said, I’ve never had an issue with battery drain after an iOS update until this latest update. I’ve kept my phone in good working order. Never over charged it. Kept everything to a minimum and now suddenly the drainage is appalling.

If my battery showed 85% on a four-year-old phone, I'd have Apple run diagnostics on the battery. The battery health indicator on the phone isn't completely accurate. You may find that your battery is more depleted than you thought and may need replacement.

I believe that you have battery drain. But the answer to your questions are in the lists underneath the graphs. Please post screenshots of the Apps you’re using. This type of battery drain is usually caused by an app or two that either need updating or delete and download a new copy.

Rrrrr34e wrote:

the latest update has drained batteries over night like you said.

Why are you not charging your phone overnight?

When to charge your iPhone or iPad - Apple Community

So frustrating and hoping those Apple coders get it corrected soon.

The problem with that hope is that it's very hard to diagnose and resolve a problem that affects only a small subset of people. Have you reported your issue directly to Apple? When you do, it's logged and will help the relevant people figure out the specific issue.

That’s the only downgrade available from Apple or Apple Authorized Service Provider , beta to latest public release. Apple Support and AASP can’t roll back to prior public iOS releases. Even doing a DFU reset installs latest public release.

same issue since updateupdate took place last night i was in work which usually my phone will be 80ish % after as i only go on it on my break however since this update left me 6% after work no apps running in background

Same problem but mine charges to 100% then drops to 1% after using phone for a few minutes but the battery keeps going! I can use the phone for several days with it showing 1% on gauge. I have an after-market battery which is brand new a few months ago and had no problems until new iOS. Called support and they would not admit to some bad code in the update (or deliberate sabotage to anyone not using "official" apple parts). Kept blaming my battery. I reminded them of the $500 million settlement against them in 2016 for a similar stunt and it looks like they're doing it again! This will be my last Apple product.

After updating to ios 18.3.1, my Iphone 15’s battery health dropped from 100% to 97% within 11 days. And 2 weeks after that it dropped to 96%. I don’t know if this is normal or not beacuse it is my first time using an iPhone.

Did you find any solution? Did the 18.3.2 fix the problem? so the replacement was needed ... still in repair shop. They told me they were able to downgrade the ios to 18.3.2 but I am dubious now and maybe I should ask them to downgrade even further to 18.3.0 or something?

[Edited by Moderator]

I recall, you’re reluctant to share what’s really going on with your iPhone. Sorry to disturb you. If you won’t share it here go to Apple Support and show them your data so they can fix it. But without evidence to the contrary, I’m skeptical of your statements with no actual evidence to support your claim.