Actually, the blinking saves energy compared to always on.
I put up an article on the front page about that WM team blog entry, and pulled out some of the LED information, and did some additional estimates for a PPC smartphone.
(
https://www.mobileread.com/forums/sho...?threadid=7241)
If you use that information, plus the battery specs and standard iLiad battery life, you should be able to extrapolate approximately how much effect the LED has on battery life.