What does the battery symbol next to a USB port mean?

We may receive a commission on purchases made from links.

Universal Serial Bus, better known as USB, is a common interface used by a wide range of devices, including computer products. Depending on the device and whether it’s old or new, you may encounter different types of USB ports; however, USB Type-A and USB Type-C connectors remain the most common. Although USB port colors can often tell you a lot about a particular port, sometimes you’ll come across symbols next to ports that aren’t easy for everyone to decipher. For example, the D symbol next to the USB ports means that they support DisplayPort Alt mode, a technology that allows video data to be sent over the USB interface.

Another symbol that you will sometimes encounter next to a USB port is the battery symbol. It is usually included in laptops to indicate which USB ports can provide power to charge connected devices during sleep or shutdown. However, you can also find it on monitors, docks, and other devices. Along with the battery symbol, some manufacturers also include a lightning bolt symbol to highlight the same features.

As mentioned, when a USB port is accompanied by a battery symbol, it usually means that the port supports the “Always On” feature, which means that the port will continue to supply power to the connected device to charge it even when you close the lid, put the laptop to sleep, or turn it off. Even if the laptop is not connected to a wall outlet, the USB port will continue to charge the connected device. Since this can cause the laptop battery to completely drain, laptop manufacturers usually include an option in the BIOS or system settings to set the level at which you want the connected device to stop charging. You can also disable the feature completely.

The power supplied by the USB port depends on the port type and generation. The power output of a USB Type-A port can typically range from 2.5W to 7.5W, while a USB-C port can go up to 15W. Although USB Power Delivery allows some USB-C connectors to push up to 240W of power using USB PD 3.2, laptop manufacturers typically reserve the higher power for charging the laptop, not the connected device, likely in the purpose of avoiding stressing or discharging the battery.

Besides laptops, monitors, and docking stations, a few other devices sometimes include a battery symbol next to some USB ports. This battery symbol simply indicates that the USB port supports charging and can power the connected device. Power output varies by device and it is best to check the device manual or manufacturer for the exact wattage.