Battery Life On Prism 7 Inch Tv How Much IPod Battery Life Do I Save By Keeping The Backlight Entirely Off?

How much iPod battery life do I save by keeping the backlight entirely off? - battery life on prism 7 inch tv

He (the 2 GB Nano 2nd Gen)

The battery life is pretty good, but I want more! Only the battery life, how much will I save to keep the backlight off completely? 2 hours? A little better? A significant amount? Any response from people with similar experiences are welcome / appreciated.