Battery Icon Beside a USB Port Usually Signals USB Power Delivery, Engadget Explains
Engadget explains that a battery symbol next to a USB port typically marks a USB Power Delivery port, which charges faster, can power laptops up to 240W and can also send power out to phones and earbuds. The icon itself is not standardized, so manuals remain the safest reference.
The marking is the most common shorthand for a USB PD port, Engadget reports. The protocol dates to 2012, before the arrival of USB-C, and was updated in 2021 to deliver up to 240W. That ceiling is high enough for demanding hardware such as high-end laptops and some monitors.
Inside a laptop, the battery-marked port works through an intelligent digital handshake between the device and the charger, which supplies the appropriate voltage and current without risking overheating. In practice, that means a laptop can charge faster than it would through a standard port.
The same port can also work in reverse. Bidirectional charging lets a laptop pass power to another device, such as a smartphone or a pair of AirPods. Some laptops go further, keeping the port active with so-called Always On charging even when the machine is asleep or shut down. Engadget cautions that leaving a smartphone plugged into a compatible laptop port can drain the laptop's battery completely, though most laptop makers include a way to switch the feature off.
The symbol itself is inconsistent across the industry. According to the USB Implementers Forum, the nonprofit corporation that created and maintains the official USB standards and whose members include Apple, Microsoft and HP, the official mark is a battery shape formed with negative space. Not every manufacturer follows that guide. Devices may show the forum's official battery symbol, a different battery logo, a lightning bolt that should not be confused with the Thunderbolt symbol, or simply the letters "PD."
Some ports support USB Power Delivery without any label at all. Engadget points to Apple's Thunderbolt ports on MacBooks as an example of PD-compatible connections that are not marked with a battery icon. When the marking on a port is unclear, Engadget advises checking the manufacturer's specifications in the user manual.