Originally Posted by joelong
The voltage difference is probably OK, but it's not good that the power supply you intend to use provides only half the current of the factory supply. This can lead to damage. Best to find a supply that provides 850 mA, or more.
No. A standard USB port on a PC is rated for 500mA and the Kindle will charge from a PC as per Amazon's specifications. Amazon don't even bundle the charger for everybody. If you plugged the Kindle into a USB hub then you'd get less than 500mA. Assuming your USB port/charger isn't faulty and isn't badly made then nothing will be damaged as devices have to be able to accept these variations in voltage and current to be certified as a USB compatible device.