I've been using Nook for two years and Nook Simple Touch for 5 months or so.
I've rooted both my devices and used them that way (until my original Nook got those screen problems and became unusable)
Starting from first days I realized that the battery life was quite shorter than advertised. In fact it was almost unacceptable, like draining %10-15 a day while standing by (at the regular screensaver)
First I thought this was caused by the rooting and custom firmware. I tried the regular disabling of services, but to no avail. After a while I decided to return to the stock 1.1 firmware (on NST). To my horror I saw that nothing changed. Then I rerooted the hardware, still same.
One day, while I was reading a book I got a call and had to leave the house very fast. Thus I bagged the NST and got out of the house.
After returning home, I left that bag in my living room and did not open it for five days. After five days I picked up the NST, which was %70 charged five days ago, sure that I had to charge it again. To my surprise I saw that the charge was still %62. How could this happen, I began to querry. And remembered that I did not manually activate the screensaver -which was my general behaviour.
After that day I did not manually activate the screensaver even once and the battery drain is never more than 1-2%/day.
I'm not an Android developer, I'm a regular computer guy (using computers for almost 30 years) but I have strong gut feeling that this may be the problem, that manually activating the screensaver is not same as activation after a time out.
I guess many people over here, being -not regular users but optimization obsessed technical people- prefer to activate the screensaver manually. Thus they have the drain problem.
If you are suffering the same problem, please test this and write your feedbacks over here. May be one of the coders can look into this problem in the end.
With kind regards