When used with Battery Charging 1.2 (BC 1.2) Standard compliant devices, the two flip-up ports are able to fast charge devices at at over 3x the normal USB rate (1.5 Amps vs 0.5 Amps) without a computer attached. Actual charging rates are device-dependent and will vary by device, so check the charging rate chart below for information on your specific device.
When used with non-BC 1.2 Standard compliant devices, or when a host PC is attached, the flip up ports and all other ports function as a standard USB hub. In this mode, devices will behave as they would when connected directly to a PC, and may or may not charge. For example, older Apple devices with a 30-pin connector are *not* BC 1.2 Standard compliant, and will only charge when the devices are powered off.