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battery health

Hi all,

I bought an iphone 11 pro max as 2nd user. it had 6 months used only and the apple warranty left 6 months. the battery health was in 97% when I bought it and now it's 89% after using only 5 months.

I charge when the battery is very low like below 10. Also I restored my all content from my 4 years old Iphone 6.

Still losing 8% of the battery health within 5 months seems terrible.

Can anybody help please?


Thank you.

Posted on Jul 4, 2021 7:11 AM

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Question marked as Top-ranking reply

Posted on Jul 4, 2021 8:22 AM

Batteries are consumables; they lose a little capacity every time they are discharged, then recharged. On average this works out to about a 1% loss for every 25 “full charge cycles” ( some will be a little more, others a little less). As one example, if you charge the phone overnight, every night (and that is what you should do; it is a best practice), it starts the day at 100%. If it drops to 20% by the end of the day before you charge it again overnight that counts as 0.8 full charge cycles (20% to 100%), or about 24 full charge cycles per month of use. For this example your battery capacity will lose about 1% per month. Of course, if the end-of-day level is higher than 20% the capacity loss will be a little less, and if it is lower than 20%, or you charge it during the day, the capacity loss will be higher. So 8% in 5 months is higher than expected, unless you are a very heavy user and recharge in more than once a day.


The absolute best way to improve the life of your battery long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern.

7 replies
Question marked as Top-ranking reply

Jul 4, 2021 8:22 AM in response to Fawaz Najimudeen

Batteries are consumables; they lose a little capacity every time they are discharged, then recharged. On average this works out to about a 1% loss for every 25 “full charge cycles” ( some will be a little more, others a little less). As one example, if you charge the phone overnight, every night (and that is what you should do; it is a best practice), it starts the day at 100%. If it drops to 20% by the end of the day before you charge it again overnight that counts as 0.8 full charge cycles (20% to 100%), or about 24 full charge cycles per month of use. For this example your battery capacity will lose about 1% per month. Of course, if the end-of-day level is higher than 20% the capacity loss will be a little less, and if it is lower than 20%, or you charge it during the day, the capacity loss will be higher. So 8% in 5 months is higher than expected, unless you are a very heavy user and recharge in more than once a day.


The absolute best way to improve the life of your battery long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern.

Jul 4, 2021 12:03 PM in response to Fawaz Najimudeen

No, it is not possible that restoring from another phone could affect the battery life.


Have you updated to iOS 14.6? iOS 14.5 and later fixes a bug in some iPhone 11’s that causes them to report battery health incorrectly. After updating if you go to Settings/Battery/Battery Health it will display the progress in fixing the bug, which can take several weeks of monitoring the phone as you use it. See→About recalibration of battery health reporting on iPhone 11 series with iOS 14.5 and later - Apple Support

Jul 4, 2021 11:57 AM in response to Lawrence Finch

Thank you for your time and respons,


still I’m not a heavy user nor I charge many times a day… I charge and use it carefully.

had doubt about the restore I made from my 4 years old iPhone 6, it had more than 120GB content… restored it from the iTunes, would there be any bug from that restore to cause this battery health damage?


thanks in advance





Jul 4, 2021 12:14 PM in response to Lawrence Finch

Yes it is in the latest version 14.6 and I noticed the recalibration message in iOS 14.5 and it disappeared after some weeks without any message or change in battery health. Anyways Hoping to follow your idea of charging overnight and still afraid that it might become less than 80% when I complete the 500 recharge cycle, up-to-date I have charged 287 cycles and it’s already 89%.



thanks a lot for your replies

Jul 6, 2021 9:07 AM in response to Fawaz Najimudeen

It’s always good to charge overnight, because it means that overnight energy use comes from mains rather than the battery.


Doing the same calculation for 50% means that you will have one full charge cycle every 2 days, or 15 per month, so converting cycles to days means it will be expected drop about 1% every 6-7 weeks on average. So 89% after 5 months is not normal. If it continues at that rate it will be below 80% within the 1 year warranty. You can also use the Get Support link at the top of the page and discuss this anomaly with Apple. They can run further battery tests remotely.


Oops, I forgot that you are a 2nd owner, so it’s at 89% after 11 months, which is not far off. Of course, you don’t know how the previous owner might have abused the battery, so that’s another factor.

battery health

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