Subject: Battery Charging Limit Concern

Your phone is supposed to charge to 100% on occasion to recalibrate the battery estimates. Let it charge to 100% so the state of charge estimates can be updated and do not remove it from the charger. After that has been completed the phone will go back to charging to the 90% that you have set for the Charge Limit. You can verify that process here in the Support Article that explains the Charge Limit. It has nothing to do with the update of the iOS version.

If you have Charge Limit set to less than 100 percent, your iPhone will occasionally charge to 100 percent to maintain accurate battery state-of-charge estimates.

About Charge Limit and Optimized Battery Charging on iPhone - Apple Support

Set a charge limit on iPhone - Apple Support

What to expect

• Your iPhone will occasionally charge to 100%—even with a lower limit set—to keep the battery percentage display accurate. This may happen more often if your iPhone isn't regularly able to complete a full charge.

"I am writing to bring to your attention an issue I have encountered with my iPhone 15. Previously, I always maintained a charging limit of 90%, and this limit was consistently applied. However, after updating to the latest software version 17.1 a few days ago, I noticed that today, after charging, the battery percentage reached 91% instead of the usual 90%[...]"

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Battery Charging Limit Reduction:

Seems you need to avoid conserving power.

Turn Off Low Power Mode:

This mode reduces background activity, dims the screen, and limits animations to conserve battery.

1. Open: Settings app on your device.
2. Scroll: down
3. Tap: Battery
4. Toggle Off: Low Power Mode (located at the top of the screen)

Update your iPhone:

Being there are new features, and for more security, I recommend backing up your iPhone, and then upgrading it.

• See my User Tip: Update your iPhone Using a Computer - Apple Community.
• Backing Up your iPhone: Be sure to back up your iPhone, that way you have something to restore your iPhone from, should anything go wrong with the update.