Not all FireWire ports of Windows-compatible computer supply power to iPod when it is connected to the computer. For this reason, you should charge iPod by connecting it to the Apple iPod Power Adapter before synchronizing with your computer. iPod's battery is 80 percent charged in about an hour, and fully charged in about three hours.
To determine if your computer charges iPod when connected, see technical document 61676, "
iPod for Windows: Does Not Charge When Connected to Your Computer".
For more information on how to charge the iPod see technical document 60939, "
iPod: About the Apple iPod Power Adapter".