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Why does the battery of my 15" Macbook pro(16GB, 2018 model) discharge to around 90-92%, while on original charger, and then slowly recharges slowly to 100% and battery health is Ok (80 cycles so far)? Is this related to recent Catalina 10.15.5 update?
MacBook
During use the battery is sometimes used during high loads even though the computer is connected to a charger because the charger alone does not supply enough power. The charging circuitry is designed to recharge the battery once its charge level drops below 93%. Your battery is fine, and this has nothing to do with Catalina.
About Batteries in Modern Apple Laptops
During use the battery is sometimes used during high loads even though the computer is connected to a charger because the charger alone does not supply enough power. The charging circuitry is designed to recharge the battery once its charge level drops below 93%. Your battery is fine, and this has nothing to do with Catalina.
About Batteries in Modern Apple Laptops
I believe that this behavior (100% => 92% then charge back to 100%, all while connected to the charger) was introduced with Battery Health Management, which was implemented in 10.15.5 latest update. The theory is that a battery that is managed this way will last longer and stay healthier longer than one that is always close to 100% when connected to a charger for long periods (some people almost never disconnect from their charger).
You can turn off Battery Health Management in the System Preferences, Energy Saver, Battery Health -- there is a checkbox, if you uncheck it, it will no longer perform active Battery Health Management, and the behavior will revert to the more traditional power adaptor charging pattern you have probably been used to. You can verify that this 100% => 92% => 100% behavior is gone.
I have left the box checked (Battery Health Management "on") on my Mac in the hope that this will prolong the life of my battery.
Thank you for your reply. I have guessed this may occur during high loads, but I noticed this only recently and sometimes this occurs without significant overload ( browsing only on safari and no other programs running in the background).. What is strange is that apple did not mention this incidence or action in its support or release notes.
Thanks for your elaborate reply. I guess as you've mentioned that this is related to the software update but what is disppointing is that apple did not notify us about this incidence. I unchecked this option and see if this periodic incidence stops showing up and this ascertain your words (that I guess you are right).
This behavior has existed since 2006. There is nothing new about it. It is part of the electronics in the smart batteries Apple has been using for years. This is not part of Battery Health Management:
When enabled, the Battery Health Management tool automatically reduces the peak capacity of a MacBook battery to prolong its life. The dialog also displays battery condition and recommends battery servicing if required. While Battery Health Management is enabled by default once the 10.15.5 update is installed, it can be disabled by the user.
Quoted from macOS 10.15.5 Update Adds Battery Health Management for MacBooks.
I have laptops running older versions of the OS. They do not actively discharge (even when inactive and connected to a charger) down to 91%-92%, once per day, and then rapidly charge back up. Others have also observed this change in battery management coinciding with the update to 10.15.5 and the introduction of the "Battery Health Management" option in System Preferences and have posted about this in these Discussions.
''When setting the Mac OS X battery status menu bar icon to display charge state by percentage, you may notice that the reported charge stays between 93 or 95 percent and 99 percent. To allow the adapter to recharge the battery to 100%, simply allow the charge to drop below 93%.''
Thanks to Kappy and steve626 for their advice. But @kappy, the battery after being fully charged then after about 24 hours on AC it automatically discharges then fully charges again while on AC.. This really disappeared after disabling the new battery health option after latest update as mentioned. But I am astonished that apple did not elaborate such an issue and I wonder this is an issue at the disadvantage of the battery to be possibly fixed later by a following update or it is deliberately designed to prolong the longevity of the battery and hence it seems preferable to keep this option enabled.
Yas81alaam wrote:
I wonder this is an issue at the disadvantage of the battery to be possibly fixed later by a following update or it is deliberately designed to prolong the longevity of the battery and hence it seems preferable to keep this option enabled.
Apple has designed this to prolong the longevity of the battery.
Possible battery health issue after Catalina 10.15.5 update
