Power consumption in Android 4.1.1 ( Jelly Bean ) is reduced by ~20%.
I wonder if somebody else could confirm it?
not exactly 20% but you can check this link it can help you to Preserve your Battery Life
http://www.techyclick.com/preserve-battery-life-jelly-bean-android-phone/
http://sparkwiz.com/mobile/android/tips-to-increase-android-battery-life/