How to get MacBook to remain at 80% charge, not 100%

The below are my answers to from a similar question here: optimized battery charging not working Ma… - Apple Community

Note that the "~2 week period" I mention is jut the period of time that I personally observed myself. This may be different with other's situations and experiences.

Just my experience...I have my MacBook Air M1 on the charger 100% of the

time. If the charge cable is unplugged, whatever internal timer is used

with Optimized Battery Charging seems to get reset after ~2 weeks.

While connected to the charger, after the ~2 week period the MacBook will

slowly discharge itself to 80% and stay there and maintain the 80%. As

mentioned, the moment the charger is unplugged, then plugged back in,

the MacBook again will charge to 100% and stay at 100% for the ~2 weeks.

If you unplug the charger from the AC outlet or the USB-C charging cable

from the MacBook, some sort of timer gets reset. When this timer is

reset, the MacBook will charge to 100%. After the ~2-week reset period

with the MacBook always connected to the charger, the MacBook will then

slowly discharge to 80% and stay there until the charger is again unplugged

from the AC outlet or the USB-C charging cable is unplugged from the MacBook.

This resets the timer where you will again have to wait the ~2 week reset period.

ejbpesca wrote:

I have selected the option for my MacBook to only charge to ≈ 80%. It remains plugged to a power adapter while in use 99% of the time. Must it stay plugged in while off to get the 80% charge feature to engage? I turn it off, unplug it for storage then plug it back to power before starting it. Does this procedure keep it from the 80% charge for battery preservation?

See this article: If battery charging is paused or on hold on your Mac - Apple Support

You need to make sure Optimized Battery Charging is activated in System Preferences or System Settings.

Once you have turned that on, the MacOS monitors the way you use the computer and will hold the charge at close to 80% for a period of time, allow it to charge up to 100% for a period of time, and then return to 80%. Sometimes it will be 80%, sometimes a slightly different %.

The MacOS has algorithms that manage this process and they are based on how you use your Mac and how often the charger is connected. It can take weeks or even months before the optimized battery charging lowers and holds the battery charge. You should just set it and not worry, as the MacOS will manage the process.

If you power it off and unplug it for storage, the battery charge will likely slowly drop over time while it is off. When reconnected to the charger and powered on, it will likely charge to 100%. Dropping to 80% will most likely occur when the Mac is in constant use connected to the charger. Other patterns of use may or may not meet Apple's criteria for holding the charge at 80%. These criteria and algorithms are not formally published but lots is known about how best to maintain lithium batteries. If using a Mac for long periods connected to a charger, the battery will last longer if allowed to go to 80% for periods of time. If the Mac is powered off for long periods of time, that won't stress the battery in the same way as staying at 100% so the optimized charging may be different.

I would simply use the Mac as best suits you, connect to a charger whenever possible, turn on the optimized charging option, and not worry any more. We use three Mac laptops on Ventura connected to chargers usually and all three are held at 80% for long periods. But it took months before the MacOS activated that level.

For total control use some software such as AlDente.