You can pull up the notification header which shows the battery level and other info while you’re playing a game by pressing the Steam button. There’s also another way to have your battery level and other handy data shown at all times in-game by activating the in-game performance overlay.

To activate this overlay, use the “Quick Access” button under the right trackpad (the ellipsis “…” button located on the right side of your Deck). Scroll down to the “Performance” menu represented by the battery icon, and turn the performance overlay on. Make sure to choose performance overlay level 2 or higher because level 1 doesn’t show the battery percentage.

While the performance overlay is visible in-game, it turns off by default once you return to the home screen. The good news is that you can enable the overlay to show everywhere in Game mode if you wish.

To do this, open the Quick Access menu and go to the “Performance” menu. Once there, make sure that you have the “Advanced View” option enabled. The button in the screenshot below reads “Basic View” because it notifies you which mode will be activated after you press it.

Once you have the advanced view enabled, scroll down until you locate a button that reads “Show Perf Overlay in Steam” and toggle it on.