You may have noticed that it takes a longer time for the Blackberry to recharge connected to your USB than the power outlet. The reason is not that the USB port doesn’t have enough juice, the problem is that it’s limited to a certain power output. The device requires 500 milliamperes to charge within the expected time. This amount can only be reached if the USB drivers are installed with the BlackBerry Desktop Software and present on the personal computer. If these drivers are not installed, only 100mA is provided, resulting in slower charge times.