There is something amiss in here. While my device is in reading mode, WiFi/3G is off and LCD is basically off; however, battery is still draining at 6% per hour. The only power that the nook should be using in this mode is to go to the next page on command, refresh the e-ink screen, update the clock, and running background checks.
One potential power drain is the constant energy required in the circuit to monitor the touch screen for refresh. Therefore, the LCD circuit is not totally asleep. I tested this theory by leaving the device in reading mode (airplane on, WiFi off, sleep timer to 20 minutes) and turned the pages only 3 times in one hour. In this one hour, the power still drains 4%. It should be noted in normal reading mode with approximately 50 page turns, the power usage is ~ 6% per hour.
In other words, for good power managerment design, the Nook should be using only 2% per hour for its reading function since 4% can be considered as non function related waste. To potentially improve the battery usage, B&N can add a feature to completely shut down the function and monitoring of the LCD screen. I hope some clever programmers/hackers can find an easy software solution. If not, it might have to be a hardware fix that we are not going to see until the next gen Nook arrives.
