If your Windows laptop screen dims when it is unplugged from the power supply, check the adaptive brightness setting. These fixes will help you resolve the issue.

Learn a simple way to temporarily disable the screen dimming feature on laptops being run on battery power.

HP's latest attempt is something called Presence Aware on the EliteBook x360 1040, which lets the machine know when you're in front of it, and dim the screen when you leave or wake up when you return.