The Specify the Display Dim Brightness (On Battery) machine setting should be configured correctly. 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 this policy setting or do not configure it, users can see and change this setting. Fix: (1) GPO: Computer Configuration\Administrative Templates\System\Power Management\Video and Display Settings\Specify the Display Dim Brightness (On Battery) (2) KEY: HKLM\Software\Policies\Microsoft\Power\PowerSettings\f1fbfde2-a960-4165-9f88-50667911ce96\DCSettingIndex