iPhone 16 Pro Max battery drain with iOS 18.5

MohammedHazek wrote:

Not charging overnight,

Charging when it goes below 20%

There's your answer. You should be charging overnight, a common misconception is that it damages the battery. Charging overnight is the best practice and you wake up with a fully charged iPhone that is designed to last the longest, an entire day. With Optimized Battery Charging.

MohammedHazek wrote:

I have updated it the same day released.

Your iPhone doesn't perform a lot of those post-update tasks and indexing while your iPhone is being used, and rather when it's on it's charger overnight. This way it can use the external power source freely and not the battery. If you did do that, it would have likely been done by now. But since you don't charge overnight, it has to index most of it only when your charging for that short amount of time, so another reason why your iPhone can be taking so long to do this, and drain more battery.

Your iPhone will always be draining battery unless charging, but that can be exacerbated further after an iOS update. After an iOS update, your iPhone must complete indexing and other post-update background tasks, which requires it to work harder and as a result drain more battery. Indexing is creating and sorting a searchable database of your data, which is why immediately after an update things are still loading in such as Search in Photos, Spotlight Search and more features powered by that. The general rule of thumb is 36-72 hours.

If you charge overnight, every night, the iPhone should not need charging until the next night, unless you spend hours gaming or watching videos. Are you not experiencing this?