Using USB Ports as a Power Source for Charging Single-Cell Lithium-Ion Batteries

摘要

A standard powered USB port can provide a maximum of 500mA to a peripheral device and 100mA for passive or non-powered ports. Accordingly, if you have a 500mA-hour battery and you can charge it at 500mA, it should charge in one hour. A 1000mA battery, on the other hand, would take twice as long to charge from the USB port.