MacBook Pro battery health dropped after macOS 26.5 update

anonymousdog_ wrote:

I purchased a MacBook Pro (M5 Pro) in November, and up until two weeks ago, my battery health was sitting at 98%. My daily usage is light, mostly consisting of streaming and school assignments.

Immediately after installing the recent macOS 26.5 update, the reported battery health dropped to 94%. I contacted Apple Support, who took logs and screenshots. During the 5 days it took for them to get back to me, the health dropped again to 93%. Has anyone else experienced a sudden, rapid drop in reported battery capacity immediately following the 26.5 software update?

I don't think there is anything intrinsic about 26.5 impacting the battery health level, although Apple might have changed its algorithm in the course of some updates, I would expect the most recent version to be closest to what is correct.

I have a 2019 Macbook Pro and here are some battery health readings from the past 6 months, including the transition to 26.2 and then 26.5:

Note that it can go up and down on its own, irregardless of the MacOS version.

Also, note this change of ~ 5% over a short period of time years back when it was much newer.

Also, this laptop battery showed 85% back in May 2025, one year ago, now it says 85.3%, one year later. The battery health can go up and down and then stay constant for a long while. I think the "noise" on this metric is several %.

If you are concerned about the battery, make sure Battery Health Management is active and connect it to AC power whenever you can. The MacOS will manage the charging and charge level to maximize the life of your lithium battery. That is really the best you can do.

<< And how do you recalibrate it. >>

Despite ample outdated and in-applicable suggestions to deeply discharge batteries, that advice is for Nickel-Cadmium batteries, and will only shorten the lifetime of a modern lithium polymer Mac battery. Deep discharge of Lithium polymer batteries has NEVER been a recommended procedure.

Re-calibration for modern Macs is done ONLY on the high side:

Charge your Mac until the battery shows 100 percent charged. This may require overnight charging.

Now continue to leave connected to the Power Adapter for an additional TWO HOURS minimum.

Your battery level should now be correctly calibrated.

anonymousdog_ wrote:

I purchased a MacBook Pro (M5 Pro) in November, and up until two weeks ago, my battery health was sitting at 98%. My daily usage is light, mostly consisting of streaming and school assignments.

Immediately after installing the recent macOS 26.5 update, the reported battery health dropped to 94%. I contacted Apple Support, who took logs and screenshots.

During the 5 days it took for them to get back to me, the health dropped again to 93%. Has anyone else experienced a sudden, rapid drop in reported battery capacity immediately following the 26.5 software update?

I do not see this as an issue.

You have an estimate of 1000 cycle count

Typically the battery out last the working life of your Mac. I would worry about something else....

The rule of thumb—if you are near the mains leave it plugged in, if you need the portability then run on the battery only—this is how you help optimize your battery charging and extend the working life of your battery by reducing the cycle count.

About Optimized Battery Charging and Charge Limit on Mac

About Optimized Battery Charging and Charge Limit on Mac - Apple Support

Determine battery cycle count for Mac notebooks

Determine battery cycle count for Mac laptops - Apple Support

anonymousdog_ wrote:

my cycle count is 82

That is a good number but it isn't relevant to the battery lifetime unless it gets close to 1000. For instance, even if the battery sits unused for several years, its battery health will drop (for lithium batteries) even with 0 battery cycle count.

Mine has 107 cycles but has 85% battery health. That means its battery life won't be used up by too many cycles, but it won't last forever either. If one extrapolates linearly (which is not how batteries behave, mine has stayed constant for over one year now) mine used up 15% in 7 years and will reach 20% (80% original capacity) in another 2 to 3 years. Except as I said, mine has stayed at 85% for over one year. SO it's not something one can predict easily. Especially with a brand new Mac and battery like yours. Only after 5 years or more will you have a baseline pattern and clearer picture of battery wear/tear and future lifetime.

Use Battery Health Management (built in to the MacOS) to maximize battery lifetime.

Just for your amusement, we also have a 2010 MacBook Air on its original battery, total of 250 cycles, and it shows 81% battery health. This Mac is so old it does not even have Battery Health Management as an option (it runs High Sierra). Another MacBook Air, 2013, had its battery fail ("Service Recommended") after only 6 years of constant use by a student who was constantly discharging and charging it as it had to be off the charger much of every day, so that battery was replaced in 2021 (not very expensive back then). Lithium batteries are somewhat not predictable in that some seem to last much longer than others. They are part of what one has to deal with with laptops, same for iPhones and smart watches. My attitude is to take reasonable steps to maximize battery lifetime (Battery Health Management active) and then worry about other things that I have some control over.

Battery health is just an estimate and can fluctuate somewhat.

Below is iPhone SE coconutBattery history when it suddenly dropped 107→55% -- re-calibrating restored it back to 106%.

That computer is a battery-CAPABLE device, It is not optimized as a battery-operated device (it is not an iPhone.)

Your computer performs best when connected to AC power, such as the power adapter. It can use the full output of the Power Adapter AND when doing especially challenging work could also freely "borrow" power from the battery. In some cases, even with the power adapter connected, the charged state may decline during very stressful work.

When used only on battery, your computer has no extra cushion of power, and may perform more slowly. However, for ordinary non-stressful tasks this may not be objectionable (possibly not even noticeable.)

In general, you should ALWAYS connect a power source when it is possible to do so, and only run on batteries (which could be somewhat slower) when no power sources are at hand. Modern Macs maintain optimum battery charge levels under program control, and will NEVER over-charge. Connected to Power is NOT necessarily charging.

When you set it down in one place, or set it down for the night, Plug it in. Then you won’t CARE whether it would drain the battery.

anonymousdog_ wrote:

my cycle count is 82

I see no issue.

I would submit to you— spend your time worry about something else independent of your battery,

let the software work for you,