Battery health

It's perfectly normal. Batteries degrade over time with usage, that's just how they work. You can expect about a 1% drop per month with average use on an iPhone.

Apple recommends replacing it when it reaches 80%

Here are some tips on maximizing battery life.

https://www.apple.com/batteries/maximizing-performance/

barazak Said:

"Battery health: I own an iphone 12,the battery health was 100 % through 7 and a half months ago ,updated to ios 15, 5 days ago I saw battery health has dropped to 99%, and today it has dropped again by 1%! Now it is 98%,it does not make sense in my opinion ,is it normal?!!!"

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About Battery Degrading:

The Battery Health drops 1-3% out-of-the-box. Why has occurred is normal. Batteries degrade as they are used, eventually depleting (which you should avoid). It cannot stay at 100%. I have had mine replaced a few times, due to high use. I do not use it as much at this moment in time. So, I have not had to replace it in a while.

Unfortunately, there is no way to know how nor when this degrade occurs. Apple recommends that you get a new battery when the Battery Health reaches 80%. So, if the Battery Health is greater than 80%, there is no need to change the battery (yet).

barazak Said:

"Battery health: But u know dropping by 1% just in 2-3 days seems strange,while the usage And habits have not changed …."

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All is Fine:

Well, sure it seems strange. But, that's just the way it is. There is no way to determine what the drop occurred.