monitor is charging my macbook, ok for battery longevity?

Sweetness00 wrote:

I have an external monitor that connects to my MacBook Pro via USB-C and is in use 95% of the time. The monitor has its own power cord to the wall outlet. I noticed that the monitor seems to be providing a charge to the MacBook via the USB-C. At the end of the day when I'm not using the computer I unplug the monitor USB-C but the MacBook battery never gets below 85%. Is this going to cause a problem for my MacBook battery over the long run?

This is not an issue.

Your battery will never over charge.

No advantage of unplugging it.

The only risk of always on the mains is the fact your battery will last longer 😉

If you are near the mains leave it plugged in, if you need portability then run on the battery. Following after that general rule use as you see fit. If on the mains 100% of the time—maybe once a month use on battery down to 50-60% say, for a little exercise—no harm there.

About Mac notebook batteries

https://support.apple.com/en-us/HT204054

Batteries - Maximizing Performance - Apple

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

Determine battery cycle count for Mac notebooks

https://support.apple.com/en-us/HT201585

About battery health management in Mac notebooks https://support.apple.com/en-us/HT211094

leroydouglas wrote:

If on the mains 100% of the time—maybe once a month use on battery down to 50-60% say, for a little exercise—no harm there.

Even that's not really necessary any longer. With the battery health management introduced in 10.15.5, if the Mac is used for a long period on AC power, it will occasionally run on battery for a brief period to provide that 'exercise'. For example, the blip on the right below where my MacBook Pro ran its charge level (blue line) down to 94% then charged back up to 100% while on AC power (indicated by green shading).

No power source can not "Force itself" on your computer. The computer System Management Controller must request voltages above 5 volts and currents above 500 milliAmps from the power-providing devices by way of USB Power delivery protocol.

They negotiate the delivered Power and Voltage levels, and the computer's System Management Controller can shut them down, negotiate different terms, or ignore them completely at any time.

Your Mac will never over-charge.

Not just ok, preferable. Running on AC as much as you can won't harm your Mac, and will extend the battery lifespan by reducing the accumulation of charge cycles.