iPhone iPod Plus

The iPod battery is a lithium-polymer. It is capable of ensuring a minimum of 500 charge cycles.

If you recharge the battery in your iPod every day, it should last between 18 months and 3 years. If you recharge the battery in your iPod less frequently, it should last as long as your iPod …
Here’s how to get the longest possible life
Do not let the battery is completely empty

For a better life for your battery, do not leave it to discharge completely. If you use your iPod infrequently, recharge it fully at least once every three weeks to prevent the battery being flat. If you go on vacation a month, you should take your iPod and recharge during this time. But you would take your iPod anyway, is not it?

Reducing the requirements of the battery

Play your music album by album or by playlist, rather than zapping a song to another. This helps to optimize the use of cache and reduces the time during which the hard disk is used.
Use AAC or MP3 format rather than WAV or AIFF. The AIFF and WAV formats are not compressed. They therefore requested the transfer of data and prevent the cache to be used effectively.
Minimize your use of the backlight or stop completely. You can specify the amount of time the backlight stays on (2, 5, 10 or 20 seconds).