To fully charge the iPod’s battery takes approximately three hours. It takes only one hour to charge it to approximately 80% capacity.
When the iPod’s battery is recharging from the computer’s FireWire port, the four bars in the small battery icon at the upper right corner of the screen flash in sequence. When the iPod is fully charged, the in sequence flashing stops and all four bars stay “lit” (i.e., black). When charging from the AC adapter, the battery icon displayed is much larger. While iPod is charging from the A/C adapter, “Charging” is displayed at the top of the screen above the large battery icon. When the iPod’s battery is fully charged, “Charging” changes to “Charged”, and the large battery icon stops flashing.
To prevent accidental discharge while you are transporting your iPod, it is a good idea to get in the habit of setting the “Hold” switch while you are not using your iPod. This will prevent accidental key presses (e.g., when you iPod is in your pocket, backpack, or briefcase) from turning on your iPod and draining the battery.
If you are running firmware version 1.2, many iPod owners are reporting unexplained battery drainage while their iPod is not is use if the Alarms option is set to “On” or “Silent”. Setting this option to “Off” under the Settings menu on iPod seems to clear this problem up.
Finally, since the iPod is never really totally “off” (in support of its instant on capabilities), Apple recommends that you fully recharge your iPod at least once every three weeks, if you are going to not be using your iPod for long periods. This will prevent iPod’s battery from fully discharging (never a good thing) while it is not being used.
Read AppleCare Knowledge Base document “iPod:// How to Get the Most Out of Your Battery” for more information.
Find more information on the iPod battery at the iPod Battery FAQ.