The Steam Deck is charged when the LED light turns off and the battery indicator in the settings menu shows "full" with a green battery icon. The Steam Deck can be a powerful gaming device, but it's essential to know when it's fully charged to ensure uninterrupted gameplay. When the LED light on the Steam Deck turns off and the battery indicator in the settings menu displays a green battery icon with the status "full," you can be confident that your device is charged and ready to go.