Q: I want to play my iPod 24/7 as my telephone hold music. Will it hurt to leave it plugged into the AC outlet 24/7? I have the first generation 30 GB iPod.
A: While you won’t damage the iPod itself by doing this, there will be an impact on the iPod battery.
When connected to an external power source, the iPod runs from the external power rather than its own battery. Once the battery is fully charged, the charging circuit shuts off and the iPod simply runs from the external power source.
In this case, the battery is not being used at all, so leaving your iPod connected to external power is the equivalent of leaving it turned off on the shelf as far as the battery is concerned.
This will result in the battery not being “exercised” and thereby failing earlier than it otherwise might. Apple recommends that you run your iPod through a full charge cycle from battery at least once a month to help preserve your battery life..