Does “Optimize Battery” keep a MacBook from running off the power adapter?

[Jaw3000]

How is MacOS “Optimize Battery” supposed to work with a MacBook Pro? I was under the impression it would restrict charging (over 80%, for example) if it drops down below this for a day, so that it only charged once per day, rather than repeatedly. But I was also under the impression this would not cause the computer to run off battery if it is plugged in, only that it would keep the battery from charging past a certain level. in order to avoid repeated/unnecessary charge cycles and charging to full capacity. Is this correct?

I did not notice anything abnormal running off power with my MacBook Pro 16” (M1 Max) on Monterey 12.0. If the machine was charged 100%, and plugged in, it would run off of the power adapter. It did not need to charge the battery, because it was not discharged. However, after updating to MacOS 12.1, I immediately noticed the machine running off of battery, even when plugged in and already fully charged to 100%, dimming the display and everything. I would have to select “Charge to full” even though the machine was already fully charged & plugged in when I started using it, in order to get the MacBook Pro to run off the power adapter and not dim the display. Otherwise, it runs off the battery all the time, even when plugged in and fully charged, and dissipates the battery rapidly when I don’t need it to. Is this normal, or a bug in MacOS 12.1?

I want to keep “optimize battery” on to avoid unnecessary max charge cycles, and am happy for the system to prevent charging if the battery is actually discharged and under a certain point, but I don’t want to be running on battery all the time while I’m plugged in. That seems like a way to run the battery down much quicker by creating unnecessary charge cycles, not "optimize" it. Not to mention the reduced performance and dim screen running off battery when I don't need it to be, affecting my usage. I’m perfectly happy for it to restrict charging above a certain point if it’s discharged, but that doesn’t seem to be what it is doing.

 

[StoneJack]

if battery is not used (ie used all time on power adaptor), battery will quickly degrade.

 

[Jaw3000]

if battery is not used (ie used all time on power adaptor), battery will quickly degrade.

I know, but that’s not what I’m asking. Should optimize battery be forcing the MacBook to run on battery when it is fully charged and plugged in?

I do use the MacBook on battery when I’m away from my desk. Which is why I’m fine with it preventing charge ups. But when I’m at my desk, working in clamshell mode or with external monitors attached, I don’t understand why “optimize battery” is forcing the machine to run off the battery even though it’s plugged in and fully charged. It seems like a bug, but I’m not sure.

 

[CalMin]

How is MacOS “Optimize Battery” supposed to work with a MacBook Pro? I was under the impression it would restrict charging (over 80%, for example) if it drops down below this for a day, so that it only charged once per day, rather than repeatedly. But I was also under the impression this would not cause the computer to run off battery if it is plugged in, only that it would keep the battery from charging past a certain level. in order to avoid repeated/unnecessary charge cycles and charging to full capacity. Is this correct?

Basically no. Optimize battery is about reducing chemical aging of the battery. It is not necessarily about minimizing cycle count.

About battery health management in Mac notebooks - Apple Support

Mac notebook computers with Apple silicon use battery health management, a feature designed to improve the lifespan of your computer's battery.

support.apple.com

Just leave the option checked, and then don't worry about how it works. Your battery will eventually fail and you will have to replace it. Until then just enjoy your Mac!

 

[Jaw3000]

Basically no. Optimize battery is about reducing chemical aging of the battery. It is not necessarily about minimizing cycle count.

About battery health management in Mac notebooks - Apple Support

Mac notebook computers with Apple silicon use battery health management, a feature designed to improve the lifespan of your computer's battery.

support.apple.com

Just leave the option checked, and then don't worry about how it works. Your battery will eventually fail and you will have to replace it. Until then just enjoy your Mac!

Except by running off battery while plugged in, it’s reducing system performance and dims the display (unless I turn that off too). It won’t let me turn on “high power mode” because it is running on battery and doesn’t seem to realize it’s actually plugged in. If I just let it go, continuing to run off battery, the MacBook will just discharge the whole battery over a course of a couple hours working. I had it go from 100% to 20% today, all the while completely plugged in. It would drain it to zero, even though I never actually needed to use the MacBook on battery. Then if I did need to unplug, it would be discharged. This is why I’m asking if this is normal for “optimize battery.” It doesn’t seem normal to me, which is why I was wondering if it’s a bug.

 

[CalMin]

Except by running off battery while plugged in, it’s reducing system performance and dims the display (unless I turn that off too). It won’t let me turn on “high power mode” because it is running on battery and doesn’t seem to realize it’s actually plugged in. If I just let it go, continuing to run off battery, the MacBook will just discharge the whole battery over a course of a couple hours working. I had it go from 100% to 20% today, all the while completely plugged in. It would drain it to zero, even though I never actually needed to use the MacBook on battery. Then if I did need to unplug, it would be discharged. This is why I’m asking if this is normal for “optimize battery.” It doesn’t seem normal to me, which is why I was wondering if it’s a bug.

Ok - I see.

I haven't noticed that, but I don't pay too much attention to it. Certainly, when I unplug, it is not usually less than 80%.

Are you using the MagSafe or USB? if you are seeing this with MagSafe then perhaps contact Apple. If not, then try a different charger - not all USB-C / thunderbolt chargers and docks have the juice for the 16".

 

[StoneJack]

I know, but that’s not what I’m asking. Should optimize battery be forcing the MacBook to run on battery when it is fully charged and plugged in?

No

 

[Jaw3000]

Ok - I see.

I haven't noticed that, but I don't pay too much attention to it. Certainly, when I unplug, it is not usually less than 80%.

Are you using the MagSafe or USB? if you are seeing this with MagSafe then perhaps contact Apple. If not, then try a different charger - not all USB-C / thunderbolt chargers and docks have the juice for the 16".

I could just let it go, and it would drain it to zero and never actually start charging. Not sure what would happen when it gets to zero. Probably shut the system down, even though I'm connected to power. This is with MagSafe, and I've only noticed it since last week's 12.1 update. It seemed normal before that. There was supposed to be a different bug with MagSafe charging on the new MacBook Pros that was fixed with this update, but I'm wondering if they introduced a new bug or broke "optimized charging" with the fix. I haven't used USB-C charging enough to notice, but I actually have not seen it happen with USB-C. I've used the Apple charger and a 100w USB-C cable. It could be purely coincidental though, since I've normally been using the MagSafe cord.

Does anyone know for sure if this is actually how optimized charging is supposed to work?

 

[Jaw3000]

No

I didn't think so. So, it sounds like a bug or a defective MacBook Pro. Has anyone else notice this occurring since the 12.1 update on MagSafe charging?

 

[astorre]

if battery is not used (ie used all time on power adaptor), battery will quickly degrade.

Just no. My work Lenovo laptop is plugged in 90% of time and I still get the same 5-6 hours of battery life like I did 5 years ago when I got it new. People tend to overthink this.

 

[J.Gallardo]

I didn't think so. So, it sounds like a bug or a defective MacBook Pro. Has anyone else notice this occurring since the 12.1 update on MagSafe charging?

I understand your problem. And no, I don’t see that behavior in my 16”M1pro. In fact, I’m still waiting for OS to “learn” from my usage, as it charges to 100% even with “limited to 80%” ticked. By now.
Every time I plug magsafe my laptop shows charging in menu-bar icon. I‘ve even noticed that plugin magsafe with laptop closed charge goes-in, with a brief sound advice (like in iOS).
It’s always automatic: plugin magsafe puts charging “on”. (And I wonder what happens to battery: Is it “disconnected“ when charge reaches 100%? Or does it keep “charging“ to sustain 100% status?

It seems you have some problem in OS, or in hardware. I know perhaps it’s silly: have you checked physical connector? How about charging through usb? Same behavior?
(Of course, try restarting, and perhaps a special safe start… OS reinstall if nothing works).
It’s the first time I hear a plugged charger does nothing on a device. Sorry: an opened laptop. (Because problem was real in prior OS in clamshell mode… This sounds different).

 

[TimmKook]

I'm just going to chime in here and say that I started using the program "Al Dente" to control my battery usage on my 2021 MBP, since I keep it plugged in almost 24/7.
I have programmed Al Dente to keep my battery between 45-55% at all times (even while plugged in) and it has worked like a charm.
This way, the battery is NOT sitting at a high charge percentage (100%) 24/7 which DOES stress the battery (basic Li-ion chemistry, you can read more on Battery University's website)
It has a free version but I decided to pay for the "Sailing Mode" feature. 25 bucks is a small price to pay for extending the battery life
Cheers

 

[julesme]

The optimized charging feature is supposed to keep your MBP at around 80% (or just below). If it's draining all the way down, it's not working correctly. As someone else asked, are you using MagSafe or USB-C port?

My new 14" actually started to do what you are describing yesterday evening, i.e., it decided it would wait until the optimized re-charge time (which it said would be "fully charged by 6:30AM"), but then it kept draining even though it was already below 80%. However, I had it plugged in via USB-C to a 20 watt adapter that I use for my iPad, so I thought maybe that was the cause of the issue. Somewhere around the low 70's %, I unplugged and re-plugged and it started charging again and stopped when it reached 80%.

Later in the evening, I moved it back to the room with my MagSafe, plugged it in there, and it immediately charged to 100%, which annoyed me because I thought it was going to wait until 6:30AM. So essentially it decided to override its optimization, even though I didn't ask it to.

 

[Matt2012]

My battery remains seems to stay at 100% when (always) plugged in via a dock even though I have 'Optimised battery charging' checked. Should it stay at 100%?

 

[julesme]

My battery remains seems to stay at 100% when (always) plugged in via a dock even though I have 'Optimised battery charging' checked. Should it stay at 100%?

Is it a new machine? It takes a few weeks to start working.

 

[Jaw3000]

The optimized charging feature is supposed to keep your MBP at around 80% (or just below). If it's draining all the way down, it's not working correctly. As someone else asked, are you using MagSafe or USB-C port?

My new 14" actually started to do what you are describing yesterday evening, i.e., it decided it would wait until the optimized re-charge time (which it said would be "fully charged by 6:30AM"), but then it kept draining even though it was already below 80%. However, I had it plugged in via USB-C to a 20 watt adapter that I use for my iPad, so I thought maybe that was the cause of the issue. Somewhere around the low 70's %, I unplugged and re-plugged and it started charging again and stopped when it reached 80%.

Later in the evening, I moved it back to the room with my MagSafe, plugged it in there, and it immediately charged to 100%, which annoyed me because I thought it was going to wait until 6:30AM. So essentially it decided to override its optimization, even though I didn't ask it to.

This is exactly how I thought optimized charging was supposed to work (keep at/under 80%) until the magic daily charge time that it learns from your usage. What your 14" is doing seems to be what my 16" is doing too. It was charged 100%, and it decided to use battery until the 'next' charge time almost 24hrs away, even though it was plugged in on MagSafe - and it kept draining down (to zero) rather than kick charging in after it went past 80%, unless I manually activated charging or re-plugged the MagSafe cable once or twice.

If I understood how the feature worked, it seems like since it was already charged at 100%, it would work like this:
(A): Stop battery charging and just run off MagSafe, letting the battery naturally trickle down to 80%, but not actually running on battery since its plugged in.
(B): If MacBook Pro has been used on battery since the last full charge, and is under 80% charge, then the feature would prevent charging past 80% for up to 24hrs until the magic time, or until manually activated, and run the machine off power if plugged in, rather than the battery.

I have not used USB-C 100w cables with the Apple power adapter enough to ascertain whether this issue is just with the MagSafe cable.

 

[Matt2012]

Is it a new machine? It takes a few weeks to start working.

Yes, just over a week old.

 

[astorre]

Yes, just over a week old.

Mine is 2 weeks old and its still not working, probably still "learning" because I dont use it at the same times every day.

 

[TheLusciousLefty]

Mine is 2 weeks old and its still not working, probably still "learning" because I dont use it at the same times every day.

It's been over a month for me. I charge it a good deal too with the MagSafe charger. I recently started using USB-C with my monitor. Does battery optimization work with USB-C. I still haven't gotten a clear answer.

 

[JPack]

It's been over a month for me. I charge it a good deal too with the MagSafe charger. I recently started using USB-C with my monitor. Does battery optimization work with USB-C. I still haven't gotten a clear answer.

Yes it does. You’ll need to be patient. It can take over a month.

 

[Micka88]

if battery is not used (ie used all time on power adaptor), battery will quickly degrade.

Oh really ? I thought that the less you use the battery, the more it will last ... And the more often you use it the more you will exhaust its potential, battery life etc ? So it is not so ?

 

[J.Gallardo]

Oh really ? I thought that the less you use the battery, the more it will last ... And the more often you use it the more you will exhaust its potential, battery life etc ? So it is not so ?

That's the thing!, the battery is ALWAYS in use. Of course, it's having a "chemical life", but more important: it seems the battery keeps connected even with charger plugged, to charge cells, or to keep charge level. It seems battery is always giving power. I don't think these new machines could do like old macbooks, where you could tear apart the battery module and the device was powered by mains. I don't think there's an electric "bridge" path now.
I imagine Apple could implement a way to (really) disconnect battery, but that could lead to new problems, I suppose.

 

[Micka88]

All would be easy if the battery can be easily replaced ...

 

[StoneJack]

Oh really ? I thought that the less you use the battery, the more it will last ... And the more often you use it the more you will exhaust its potential, battery life etc ? So it is not so ?

if you don't use battery, it will quickly (actually very quickly) degrade. Battery is designed to be charging and recharging, thats' its purpose. It will gradually degrade over years and 80% capacity should be replaced. But if battery is not used (for supply of energy), its ability to be recharged will drop quickly so your max capacity will fall quickly

 

[wilberforce]

if you don't use battery, it will quickly (actually very quickly) degrade. Battery is designed to be charging and recharging, thats' its purpose. It will gradually degrade over years and 80% capacity should be replaced. But if battery is not used (for supply of energy), its ability to be recharged will drop quickly so your max capacity will fall quickly

This doesn't tell the whole story. Also, what is true for one type of battery (like Ni-Cad) can be the opposite for another type of battery (like Li-ion).
If a Li-ion battery is maintained at 100% charge it will degrade.
The best way to preserve a Li-ion battery long-term is store it at 50% charge and keep it cold.

DJI "intelligent" drone battery packs automatically self-discharge to ~50% after 10 days of non-use, to self-preserve (without even being attached to a drone).

From Apple:

From DJI:

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com