Nook Glowlight (2013)
Those who say something like "android on any book wildly eats battery" is dedicated to:
1st measurement (don't know how to create spoiler for many screenshots, sorry; link for screenshots in the end of the post)
Time since last charging 33d 5h
Almost 1d 8h screen on time (32 hours)
In fact, since the screenshots, I lived about 7 more hours of standby.
The device is 4.5 years old, everyday usage (not special test), I didn’t do anything especially to increase the working time, the main programs used are ZXReader for reading and ReLaunch as launcher, backlight is turned on 95% of the reading time, the level on the screenshots, Wi-Fi is turned on extremely rarely (download books, screenshots)
2nd measurement
Time since last charging 24d 3h
Almost 1d 18h screen on time (42 hours)
3rd measurement
Time since last charging 18d 18h
Almost 1d 20h screen on time (44 hours)
Source (4pda forum, Russian)
Sorry for my bad English