What can I do to extend the life of the battery?

I have:

enabled power saving mode

set the brightness of the backlight to the very min

backlight time: 2 secs (min without being off)

EQ: off

crossfade: off

It's a 16GB and I'm only listening to music (anywhere from 192kbps to 320kbps), unless the clickwheel is so sensitive in my pocket that the backlight keeps turning on, it only lasts for about 6-9 hours at a time.

don't know what to do because it was a gift from my ex and I don't have the receipt (although it is within the 1 year warranty.) I haven't tried resetting the settings or returning it to factory state yet and I've recharged the battery for over 4 hours using my PC after letting it fully drain.

Thanks in advance, I'm starting to have a feeling it's a problem with all 5th gen nanos after reading through some other forums.