Q: Will I lose everything I have on my iPod when the battery is changed? Also, I received an 80g iPod for Christmas; is this a 4th or 5th generation? How do you tell?
A: No, changing the battery does not result in any of the data on the iPod being lost. The full-size iPod models use an internal hard disk, similar to the one found in your computer, which is a permanent storage device. In the same way that your computer retains data when it’s unplugged, so does the iPod itself.
Likewise, although the iPod nano does not have a hard drive, it uses persistent flash memory, which also does not require a power source to maintain its content.
Changing the battery will result in some of the memory-based settings being reset (such as backlight timer and shuffle mode), but these are merely configuration options that can be easily reset.
To answer your second question, an 80GB iPod would be a fifth-generation iPod, as the fourth-generation units were not made in that capacity (60GB was the largest fourth-generation iPod model). Further, the fourth-generation iPods did not support video playback capabilities.
There have actually been two different releases of the fifth-generation iPod: The original 5G iPods were released in October, 2005, and came in 30GB and 60GB capacities.
In September, 2006, Apple introduced an “enhanced” fifth-generation iPod (sometimes also referred to as the “5.5G” iPod), in 30GB and 80GB capacities. At the same time, a firmware update was released for the older 5G iPods, providing many of the 5.5G features to the older models. The only difference between the older 5G and newer 5.5G iPods is the brighter screen on the newer models, slightly improved battery life, and a “Search” feature that can be found under the “Music” menu on the iPod.
Original 5G and Enhanced 5.5G iPods can also be identified by the packaging.