Logitech MX Ergo trackball battery status LED

Your trackball has an LED to indicate battery status. When you turn your trackball on, the LED lights up to let you know the battery status and then turns off to conserve battery power.
When the LED is:

• Glowing green — Up to 100% battery life
• Glowing red — 10% charge remaining

You can also use Logitech Options to receive battery status notifications, including low charge warnings. If you don’t have Logitech Options, you can get it from the product’s Download page.