Here is my battery life over the past 4 days... last night you can see i left the phone off the charger at 88% and disabled background data use... this left a stairstep decline at 1.5% decline per hour until 8am it was 74%. For some reason with disabled background data use, my touchdown exchange mail still pulled in messages, gmail wasn't. No other app would work for me with background disabled.
No matter what I've done to conserve battery life
it averages a 1% battery life decline every 6.9 to 7.3 minutes. In other words, it lasts approximately 12 hours give or take .5.