Can I tell my Mac to charge to 80% only?

Question

I leave my MacBook plugged in for days at a time, so the battery stays charged to 100%. Despite Apple claims to the contrary*, I believe that the battery's capacity would be better preserved if I could keep it at an 80% state-of-charge, so that is my goal unless someone can convince me that taking it above 80% charge has benefits to counterbalance any drawbacks.

https://www.apple.com/batteries/maximizing-performance/

Here are various options, (1) being my most preferred:

1. A setting to automatically maintain battery at 80% SoC (like my Tesla has)
2. A setting/command to use the AC adapter for running power only ("not charging" state)
3. A command to tell my Mac to totally ignore the AC adapter power

(2) could be cobbled into (1) with some kind of script. Even if not possible from the Mac itself, (3) could be cobbled together with an IOT switch. But with (3), it's unclear the lower maintained SoC would outweigh the cost of the additional cycling.

* As of 11 Feb 2022, I can no longer find Apple claims that it's best to fully charge the battery.

Is there any app, command or setting that would let me disable charging from the power adapter?

Answer 1

Use bclm (Apple Silicon with macOS 13.0 or higher and Intel Macs)

Follow the instructions on GitHub:

1. Download signed and notarized binary from releases.
   (Alternatively, you can also get it from Homebrew or compile it manually. Read the GitHub readme for more details.)

2. Extract battery tool

$ unzip bclm.zip
$ sudo cp bclm /usr/local/bin

3. Set battery limit

$ sudo bclm write 80

4. Verify battery limit to 80%

$ bclm read

5. Reset the limit back to 100% when needed

$ sudo bclm write 100

Notes:

• It might be better if you set it even lower, for example, 60% or 70%. Then, before you need to use it on battery for a long time, bclm write 100. You can automate this switching between 80% and full using launchd (read man launchd.plist).
• macOS show charge approximately 3-5% greater than the real value, so it may feel like the tool is not working initially. Use coconutbattery (GUI) or ioreg -l | awk '$3~/Capacity/{c[$3]=$5}END{OFMT="%.3f";max=c["\"MaxCapacity\""];print(max>0?100*c["\"CurrentCapacity\""]/max:"?")}'^[1] to calculate real battery charge level.
• If you are using macOS Catalina or higher, you need to turn off the "Optimised battery charging" function for the tool to work properly, otherwise, the value you set might be overwritten.
• There is also a GUI version: charge-limiter. Both work by setting the BCLM key in SMC to a custom value.

For Apple Silicon Macs and macOS 11 (Big Sur) and higher, use AlDente.

Alternatively, there is a more lightweight tool with a command line version: battery.

^{[1] _{No longer works with Apple Silicon Macs.}}

Answer 2

macOS 10.15.5 on a Mac notebook with Thunderbolt 3 ports has this option (even a bit smarter) embedded, see Optimised battery charging.

https://support.apple.com/kb/HT211094

Answer 3

You can try AlDente (there is also a Pro Version):

• Charge Limiter allows you to set your maximum charging percentage between 20 and 100 percent. You can either set it by using the slide bar or by typing in the desired percentage in the field above and pressing enter afterwards.
• Discharge - This feature allows your MacBook to run completely on Battery even if it is plugged in. Therefore, you can actively discharge your MacBook to a more healthy percentage. Unfortunately, while Discharge is activated, clamshell mode is not supported due to technical limitations.

Answer 4

There are some new options for Macs with Apple Silicon. Apple refers to their system for battery charging as "Optimized Battery Charging"; the OP's question seems to be asking about "Limited Battery Charging". I feel that many of the issues reported with Apple's "Optimized Battery Charging" have to do with how Apple has optimized it.

Apple's software is mostly all proprietary and closed-source, so there's no way to know for sure what's going on, but we do know that Apple relies on periodic "battery calibration" for reporting the state of charge. We also know that battery calibration requires occasional charging the battery to 100%.

Therein lies the problem:

Achieving the battery longevity benefits of maintaining an 80% charge level
VS.
When & how often to re-calibrate the battery by charging to 100% to maintain accurate reporting?

How well Apple has balanced these competing objectives may depend quite a lot on the individual user's usage profile. Which may explain the number of questions/complaints.

Also: Given that Apple's "calibration" keeps the battery between 80% charge and 100% charge, one might wonder how effective a calibration can be if it's kept in such a narrow range. There's a good article at the Battery University explaining how calibration works, and why it's valuable. But this is not how Apple does it... suffice it to say that apparently Apple has not read (or doesn't believe) this article.

If your experience with Apple's "Optimized Battery Charging" leaves you feeling less than enthusiastic, perhaps you should investigate one of the apps that implements "Limited Battery Charging". Here's a short list of apps that implement "Limited Battery Charging" for Macs with Apple Silicon:

1. AlDente - Charge Limiter, commercial edition

2. AlDente - Charge Limiter, open-source edition

3. Battery-Toolkit; fm 'mhaeuser'

4. battery; fm 'actuallymentor'

5. batt; fm 'charlie0129'

6. bclm; fm 'zackelia' - see this issue before installing

In general, these "Limited Battery Charging" apps focus almost entirely on battery longevity, and leave the periodic calibration function to the user. This may amount to simply disabling the charge limiting function, and allowing the charger to charge to 100%.

Answer 5

There is also Energiza Pro. It supports Apple silicon MacBooks and allows you to set flexible charging limits. (Disclaimer: I'm the developer.)

Answer 6

Tried below and it worked.

Open Terminal and run

xcode-select --install
git clone --recursive https://github.com/DevNulPavel/osx_battery_charge_limit
cd osx_battery_charge_limit
sudo python3 main.py -s 80

I set limit to 70 and it does stop charging until 72%

Answer 7

If you don’t like the many open source options in this Q&A - one more lightweight app that works well is Charge Limiter. It doesn’t work on Apple Silicon, so it’s for Intel based macOS systems.