Macbook pro battery charging matter

The MBP (15", 2018, Sonoma 14)) never leaves the desk, so is always connected to the electricity power. The battery level stayed at 100% all the time. Lately, I started shutting off the MBP every night, and it stays unplugged for ~10 hours. This had been going on for ~ 2 weeks. Lately, the MBP started decreasing the battery power to 80% and leave it like that the whole day. I go out, just close the lid, come back and it is still at 80% - charging on hold. Now, if I shut down the MBP at night, and the next day, the battery level is still at 80%, but but itwould say that it will be charged to full by 10:30, and that happens. But, after a while, a few hours later, it goes slowly back to 80% and stays that way.


By the way, this MBP never gets heated up, I never hear the fans, except when an update is going on. There are few apps working, quite a lot of tabs open etc. Cool at touch and so on. battery cycle is at 207. It was bought in mid 2019.


Yesterday, I left it on all night, that is the lid closed, the MBP sleeping for ~10 hours. The battery level is still at 80%, charging on hold. I think, I'm going to keep it this way (always plugged in, but not shutting off, sleeping at night) till next Sunday, and then use it on battery the whole day on the Monday after, to give the battery some work experience, and then continue to use it for the next month always on power without shutting it off. And, give another full day's work on battery after that month.

Any thoughts? Thank you!

MacBook Pro 15″

Posted on Oct 1, 2023 1:00 AM

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Question marked as Apple recommended

Is optimized battery charging on? This can explain this behavior. Go to settings>battery to check that. You can turn the function off to see if the battery issues persist, but after checking, I reccommend that you turn the setting back on again, as it is an important feature that helps keep your battery safe.

Posted on Oct 1, 2023 2:31 AM

22 replies

Oct 19, 2023 6:07 AM in response to chdsl

Yesterday evening, I decided to shut down the MBP at night with 100% battery. In the morning today, at 8:45 the battery had that 100% charge. So, decided to use it on battery to check how it is faring. Same work/usage as in a normal day. At 14:45, that's 6 hours later, the battery charge was 35%. Well, not bad for a made in April 2019, but officially a 2018 15" MBP, nearly 4 and half year old battery. Cycle count 209. Temperature level stays between 26.5-28.5°C.


Once, the MBP battery reaches 20%, it'll be charged and will go back to the optimised charging cycle for next few weeks. If the MacOS/MBP remembers how I use it, then it'd fall back to 80% and to the Desktop Mode. I hope. :)

Oct 19, 2023 9:23 AM in response to chdsl

After bit more than 7 hours, the battery charge was 25%, that is, 75% of the battery charge got used in 7 hours, which means, more or less, that The MBP would've worked a bit more than 9 hours 15 minutes if the battery was fully drained. It was supposed to go about 10 hours, when new, according to Apple. Not bad, really!


I think, the best way for this MBP is to use it on power adapter in the day and shut it down for the night. That way, a certain rest is given to the MBP and for the power adapter. Anyway, while on power adapter, the battery is still charged in the optimised mode, most times bypassing the battery, never completely going to 100%, if at all not for long. Also, all apps are quit before shutting the MBP off. In the morning, it takes just a few minutes to boot the MBP. Ram cleared with no residue, indexing is a normal thing that happens in the background.

Oct 20, 2023 1:14 AM in response to chdsl

Well, the MacOS/MBP appears to have learnt my "charging" habits in optimised charging mode. Yesterday night, the MBP was shutdown, power cable taken off the slot, both the MBP and the adapter was resting. Today, after about 20 minutes after booting the MBP, and on power adapter, the battery charge started going down.

And, the charging is on hold, the MBP is in the Desktop Mode.


So, in a way, my supposition was right, the MBP could be shut down at night, and rebooted in the morning, or at any working time, the MacOS/MBP would go back to the Desktop Mode, of course, in the optimised charging mode. Sonoma is doing quite well in this. :)


Any ideas, suggestions?

Oct 21, 2023 1:11 AM in response to chdsl

Instead of shutting down the MBP for the night, I left it sleeping and on power adapter at 80% battery charge, which was there the whole of yesterday. Now I have a new communique from the optimised charging mode. Quite interesting one at that.


well, have to wait and see, what it'll do at 14:30 and for the rest of the day.

Oct 21, 2023 5:54 PM in response to chdsl

chdsl wrote:

What's also interesting is that the battery capacity had gone up by ~3.5%! So, it appears that resting the MBP is advantageous for the battery -- not sleeping and connected to power, nor just sleeping on battery -- just simple resting fully shut off. 😊👍

No, the Battery Capacity percentage change is due to the fluctuation of the Battery's Full Charge Capacity (FCC). If you were to monitor the Battery's raw FCC values you would see it fluctuating up & down all the time. The Battery Capacity percentage reported by macOS is just a snapshot at the time it was calculated. I have no idea how often this Battery Capacity percentage is recalculated.


I don't have enough experience of monitoring of the Battery Capacity percentage or FCC with Apple Silicon Macs, but I have studied the battery behavior with Apple Intel laptops. The FCC raw value of Apple Intel Macs tend to fluctuate up & down even when healthy, but this fluctuation increases as the battery ages & wears. IIRC a small 50mAh change in FCC raw value translates into about a 1% percent change in Battery Capacity. I have noticed normal FCC fluctuations of even 300mAh for even a good battery. I only begin to worry about the Battery if that FCC value jumps by 400mAh or more.....usually those fluctuations are more important as the battery ages and nears the 80% capacity.

Oct 22, 2023 12:21 AM in response to HWTech

You see, I never cared/worried much about battery capacity when I was using Linux and Windows. We have Linux/Windows laptops that has the FCC less than 75%, more than 1400 cycles, but some of them (Lenovo and Medion) ~5 hours on battery, and there is an Acer Swift that runs > 10 hours. I just got involved in this battery charging "madness" only after buying an Intel Mac. Anyway, I like the Mac, especially MacOS apps - very easy to use.


Coming back to our matter, the FCC had gone up that 3.5% and stays there since I reported it here, the FCC fluctuating by 0.1% up and down time to time. 😊


HWTech wrote:

I don't have enough experience of monitoring of the Battery Capacity percentage or FCC with Apple Silicon Macs, but I have studied the battery behavior with Apple Intel laptops.

Thank you for taking time to reply. I'm glad for any insight on this matter. I'm not going to worry about the battery of my MBP, but it had just become a pastime. I'm sure it is going to last another 4.5 years. After all, it was high-end when first sold by Apple. 😊

Macbook pro battery charging matter

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