Rapid battery drain in iPhone 16 Pro after iOS 18.3 update

This is normal. After an update, your iPhone has to carry out several background tasks including indexing to complete, in which they can consume more battery than normal. When the update is fully complete, which can usually take a few days depending on your amount of data, your iPhone's battery will return to normal.

Please also read my User Tip: Addressing the Common Increased Battery Drain and Thermal Temperature Conditions Your iPhone May Face After Setup and Updates

justcn wrote:

16 pro users help me pls. I updated to 18.3 last Feb 4. Slept at 11 pm, feb 5 at 57%. When I woke up at around 6:30 am the next day, it goes down to just 50% 🥲 Used it as usual (fb,ig, messenger, imessage) and it drains to 33% (8:27 am).

Feb 6, I charged my phone to 90% at 10:31 am and it dropped to 20% at 6 PM.

What should I do? Background app refresh is off. Location services is off. I do not have whatsapp installed 🙁

settings - battery - what app(s) is draining your battery.

justcn wrote:

https://discussions.apple.com/content/attachment/1bbc4c3d-a31f-443c-8ee0-184e59ea5e3a

Well, your on screen time is 11 hours with the majority of it being on Facebook.