iphone 15 battery health drop 1% each 20 days is it normal

Your maximum battery health is relative to when it was new, the more you use your iPhone, the more it will chemically age. Your iPhone is expected to drop 1-2% battery health every month or so, and it isn’t always linear. Meaning some months you may not lose battery health at all, or one month you lose more than expected.

Learn ⇢ iPhone Battery and Performance - Apple Support

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* When you use your iPhone, its battery goes through charge cycles. You complete one charge cycle when you’ve used an amount that represents 100 per cent of your battery’s capacity. A complete charge cycle is normalised between 80 per cent and 100 per cent of original capacity to account for expected diminishing battery capacity over time*

Learn more ⇢ About the battery and performance of iPhone 11 and later - Apple Support

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How many Charge Cycles have occurred on the phone when you look at the Battery Settings?

Adding on, batteries of iPhone 15 models are designed to retain 80 percent of their original capacity at 1000 complete charge cycles under ideal conditions.

"Ideal Conditions"* exist only in a perfect world. You might want to also include a link to the "*" to see all the disclaimers.

One of the many footnotes:

All battery claims depend on network configuration and many other factors; actual results will vary.

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