When I remove the charging cable, the brightness of the screen is reduced to 50% from 100%. If I plug the cable back in, then it goes up to about 75%. It then drops again to 50% when I remove the cable.

Screenshot of brightness 50% Screenshot of brightness 75%

I would like to prevent the screen brightness from changing unless I change it manually with the screen brightness keys. What am I missing? I have the following configuration:

  • System Preferences > Battery > "Slightly dim the display while on battery power" is off.
  • System Preferences > Battery > "Turn display off after" is set to never.
  • System Preferences > Displays > "Automatically adjust brightness" is off.

Screenshot of System Preferences, Battery Screenshot of System Preferences, Displays

macOS Monterey 12.3 (21E230).

2 Answers 2


I just discovered what the problem was: low power mode.

Screenshot of System Preferences, Battery, with low power mode enabled

If System Preferences > Battery > "Low power mode" is enabled, then the screen dims when you remove the charging cable, regardless of all the other settings saying that the screen must not be automatically dimmed.

This also happens when you click "low power mode" to enable it, so it looks like this is a low power mode feature: as soon as low power mode is activated (in this case, when switching to battery power), the screen gets dimmed to 50%.

There doesn't seem to be any way to keep low power mode enabled and also prevent automatic dimming. Turning low power mode off solves the issue.

  • My mac's low power mode is set to 'never' and it still does it when the charging status changes. Commented Sep 19, 2023 at 18:06

it's different in Ventura now. In addition to doing all that, you also need to go to the Settings/Displays/Advanced... then tick off "Slightly dim the display on battery"

  • 1
    Take time to reread the question: "Slightly dim the display while on battery power" is off.
    – Thinkr
    Commented Jun 1, 2023 at 7:09

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