What is the difference between a battery charging USB port and a standard USB port?

USB ports are convenient for charging battery powered devices, but this can be slow on a standard USB downstream port (SDP), which only supplies a maximum of 500 mA @ 5V.

To meet the demands of high-current and battery-powered USB devices, the battery charging specification (BC v1.2 adopted in 2010) defines two types of charging ports: dedicated charging ports (DCP) and charging downstream ports (CDP). Mechanically, the USB charging ports use the same standard Type A USB connector. The only difference is the power available on the USB ports.

A DCP is used strictly for power, requires no host connection and offers no data transfer capabilities. This has resulted in the proliferation of USB chargers that provide a USB Type A connector. DCPs are also finding their way into cars, AC wall outlets and portable chargers.

Sealevel’s 7-port USB 3.1 hubs and 4-port USB 3.1 hubs have one port configured as a Charging Downstream Port (CDP) capable of supplying up to 2.4A of current to a connected device. The remaining CDPs supply up to 1500 mA to each connected device. This allows them to easily power or charge CDP compliant devices. All CDPs are USB Battery Charging Specification BCv1.2 compliant, ideal for charging batteries or powering high-current USB peripherals.