Policy
Specify the display dim brightness (on battery)
This policy setting allows you to specify the brightness of the display when Windows automatically reduces brightness of the display. If you enable this policy setting, you must provide a value, in percentage, indicating the display brightness when Windows automatically reduces brightness of the display. If you disable or do not configure this policy setting, users control this setting.
613ac92bc8a3 DisplayDimBrightnessDC Registry
Copy registry mappings
HKLM\Software\Policies\Microsoft\Power\PowerSettings\f1fbfde2-a960-4165-9f88-50667911ce96\DCSettingIndex Policy notes
This policy setting allows you to specify the brightness of the display when Windows automatically reduces brightness of the display. If you enable this policy setting, you must provide a value, in percentage, indicating the display brightness when Windows automatically reduces brightness of the display. If you disable or do not configure this policy setting, users control this setting.