lol
iPod's battery life altogether is so short...
but that's another story.
capacity as in how much space you've used up on it???
not at all,
the battery is wasted by actual use.
Either that or your battery can't hold a charge and it wastes even when the iPod is off.
I recommend lowering your brightness, or even turning it off during the day. Using the shuffle function sparingly, and not waste a lot of time "browsing" and scrolling wastefully through your artists.
hope I helped
:]