iPhone 15 Pro Max battery health dropped by 5% in 1 month after iOS update

When you updated the iOS version on your iPhone 15 Pro Max, then you also initiated calibration of the battery in that iPhone. You, therefore, saw the most updated battery health. You have an iPhone 15 Pro Max so the battery health should be at 88% or better.

Battery Health & Performance 

Your battery health is fine and is undergoing normal usage. iPhone batteries, like all rechargeable batteries, are consumable components that become less effective as they age. You should change out the battery once your Battery Health reaches below 80% which will take over 2 years to reach under normal usage. Until then enjoy your iPhone.

Here is some more reading on an iPhone battery and its performance 👉 iPhone Battery and Performance - Apple Support

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Keep an eye on things. It is not unusual for an update to consume 2-4% in just a few days after the update.

If the same type of drop continues next month, make an appointment at the Apple Store or take the phone to an authorized Apple service shop to have the battery checked and tested.

You can find a list of authorized service shops in your area using this link:

Find Locations

If you want to get an idea of how the battery is doing overall, check to see how many Charge Cycles have occurred with your phone's batteries and post back with that information.

‏my battery health has decreased by 5% in 1 m

Sir, there was a 5% decrease in the first 11 months

Which is it? 5% in one month or 5% in 11 months?

What is the current Maximum Capacity? Settings > Battery > Battery Health & Charging

After 11 months, if the Maximum Capacity is 88-90%, your battery is performing normally

How many Charge Cycles on the battery?

mahboob133 wrote:

Sir, there was a 5% decrease in the first 11 months

Yep, it is now correctly calibrated. On average you can expect about 1% per month drop. Again this is an average over many months and some months will not drop at all and other months will drop more. After 11 months, if your battery health is 89% or better, then you are ahead of the average and doing better than most.