Chosen Solution
Recently, I replaced the 30GB drive with iFlash Solo and 128 GB SD card. Now I notice that the full charge on the battery does not last for more than a day. How long is it supposed to last?
From what I found with a quick Google search, the battery should last for 14 hours. Rechargeable batteries wear down over time, so it is normal for it to not last as long as it used to. If this is a big problem for you, you can replace the battery. iPod 5th Generation (Video) Battery Replacement