“Replace the Battery. If you have an iPod that’s out of warranty, consider installing a higher-capacity battery. The capacity of a battery is measured in milliamps (mAh). Companies such as Newer Technology and Sonnet Technologies sell replacements that have higher mAh ratings than the original iPod batteries. Get one of these, and you’ll up your iPod’s play time.
 
How much? I replaced the 1,200mAh battery in my first-generation 5GB iPod with a $20 2,100mAh battery from Newer Technology. According to Apple, the original battery should last up to 10 hours per charge. With the Newer battery on board, my iPod played music continuously for 21 hours and 25 minutes.
 
If you’re mechanically inclined, it’s fairly easy to replace the battery in a first- or second-generation iPod. But newer models are tougher nuts to crack. For instance, the iPod mini is particularly difficult to open. And the third-generation iPod includes a thin cable that’s attached to both the motherboard and a connector on the back plate; open this model the wrong way, and you could break the cable, which will destroy your iPod. For this reason, it’s safest to have a professional install your new battery. iPodResQ offers a battery-replacement service for $64, and Other World Computing (eshop.macsales.com) will install a Newer Technology battery for the price of the part plus a $39 service charge.”