vaguelyaware.com

I found a little trick to get your iPod to display what looks like minutes remaining on the battery in a numerical value instead of that silly ambiguous graphic.
Open the Terminal (with the iPod docked and available as a hard drive) and type:

touch /Volumes/your_iPod's_name/iPod_Control/Device/_show_voltage

Replace your_iPod’s_name with the name of the iPod as shown in the Finder. Once you eject, you should see a number in the upper right, this may require a restart, mine didnt and now shows somehting like 471, if the backlight kciks on it drops about 10%.
If you wanna undo this, just ‘rm’ the file.