When our 3G iPod was getting only two to three hours battery life from a charge, we decided that it was time to try one of those third party iPod batteries people have been talking about for years.
They said the iPod was fairly easy to pop open the iPod and change the battery despite the lack of any physical openings. Well, whoever "they" are, they totally didn't account for our lack of manual skills. It took us a total of an hour and a half and two people to get this thing open.
The problem comes from the fact that the metal back and the plastic front to the iPod are flush, so there's no easy way to pull the two apart. The Fastmac battery kit comes with two blue prying tools in order to do so. Because these tools are plastic, and thus, wear down easily when shoving it up against the iPod's metal, if you don't get the iPod open on the first few tries, your tool becomes less and less useful. You wouldn't want a metal tool, because it'd scratch up your precious MP3 player's finish. Thus, it takes a long ass time to get the iPod open.
Once that was done, everything else was cake. Take out the hard drive, disconnect the cable, and replace the battery. You'll have to exercise a bit of care, as the connectors are pretty fragile, but nothing you can't do in less than four minutes.
The new battery got us about seven or eight hours of battery life, around the same as the original battery. An iPod as good as new—save for all the dirt and scratches from years of use—for just $19. Definitely a good deal.
Be prepared to set aside a block of time in order to get your iPod open if you're not quite so handy. And don't be afraid to use a lot of force when prying.
Product Page [Fastmac]
Image courtesy Apple Links