Laptop and Tablet users running Windows 10 can get into a problem where they are not able to control the brightness of the display screen. In fact the problem sequence is something like this. You are using your laptop and suddenly the brightness level decreases automatically. Frustration gets added up when you find that the brightness doesn’t respond to the keyboard brightness + and – key (if your device have one).
Don’t worry, you are not alone and the biggest relief is this isn’t actually a problem with Windows 10, but it is a Battery saving feature! Windows 10 has a Power saver feature in which it switches the device to Battery saver mode when power falls below 20%. And Battery Saver mode’s one of default functionality is to reduce the screen brightness to 75% or so, in addition to stopping Push Notifications and some Background processes. Manually increasing the brightness doesn’t do anything until Battery Saver mode is active.
Click or tap on Battery Icon on Taskbar to open Power Menu, you will see Battery saver active in the form of colored box. Click on it to toggle it and you can now control screen brightness.
And if you think that 20% Battery is a lot for you at would like to have your own number there, you can do so:
1) Type Battery Saver in taskbar search box and click on first result which is Battery Saver System Settings.
2) Click on Battery Saver settings.
3) Move the slider to desired level. It can only change in multiples of 5. You also got option to disable Lower screen brightness while in battery saver. When you uncheck it, Battery Mode will have no effect on screen brightness, but still applies other power tweaks like stopping Push Notifications and Background processes.