[ZodWallop]

Originally Posted by ProDigit

This is a quick guide for those who are looking to maximize battery life on their book reading devices.
Most of it is common sense.

In my case, I'm using an Amazon Kindle Oasis; but many devices have similar settings.
I'll try to organize them in order of importance:

1. Disable wireless connections
   Just (down)load books and literature on your device, while the device being plugged in the power adapter. For an e-ink device, the wireless and indexing, is using up most of your battery, so do it while plugged in.
   After your device has downloaded all books into the memory, use either 'airplane mode' or disable wifi. Also disable Bluetooth, when you don't need it.
   
2. Dim screen light
   To get the correct display brightness setting according to studies done, your screen should be slightly brighter than your surrounding. Turning up brightness too much may be nicer to look at in the short term, but will tire out the eyes quickly in the long run, and can cause eye wear.
   On most e-ink devices, setting the back or front light to 'off' would be good enough.
   Especially when reading in outside light, save your eyes, and set the reader to 'night mode' if it supports it (white text on a black background).
   Screen light should be used in dim to no surround light only, and not too bright. Aside from burning your eyes, it will burn your battery too.
   
   If you are reading on a tablet, more than often, the darkest backlight setting is good enough for most indoor use.
   Unlike with e-ink devices, the lighter it gets outside, the brighter the backlight has to be set.
   
   Certain tablets allow for further dimming of the screen than the factory minimum.
   
   The Apple Ipad has a 50% dim in one of their zoom filters natively built in the OS. The procedure is found here: https://www.mobileread.com/forums/sh...d.php?t=285069
   
   Windows devices can install an app called dimscreen, found here: https://dimscreen.jaleco.com/
   
   Android devices can find an app called Screen dimmer, found here: https://play.google.com/store/apps/d...rand.brightcom
   
3. Turn off touch screen
   Some devices, like the Kindle Oasis, have page turn buttons. Since most E-ink devices use almost no power at all, aside from the wireless connections, and the screen light, the touch screen is the third heaviest battery eater on your device. If your device supports it, turn off the touch screen will save you battery.
   
4. Remove external memory cards
   If your device supports SD or Micro SD cards, you can further save battery by loading the books on internal memory only, and remove the (micro)SD card. The internal drive is 'always on' or always powered, but any external drives are only powered when they are connected. You can save a few more minutes to hours of battery life, by not using external cards.
   In case of a small internal memory space, this might mean to decrease your library (eg: by removing books that you already read, or aren't going to read anytime soon).
   
5. Focus on text based books, as much as possible
   Ebooks come in all formats and sizes.
   text files (.txt) are the easiest on internal memory, battery usage and CPU processing power.
   They do not always present well on an E-ink device, since the text does not have any sort of formatting.
   Ebooks like .mobi, .lrf, .epub, etc... are compressed HTML pages. They require little more CPU, but have nice formatting available, that makes it easy to read, and probably the best tradeoff between formats.
   Try to read books in formats that your reader or device natively supports.
   Many tablets support many formats, but for instance, Kindle formats, need to be read with a Kindle reader app program, that might be less efficient, battery wise.
   
   If there's no other way to get a book in a txt, html (epub, mobi, lrf) or doc format, reading books created by jpg or tiff files, or reading PDF files, require most processing power of your device.
   While possible to read them, these formats do require significantly more CPU power, and thus, consume more battery life as well....
   
   And lastly, audio/video books.
   Some ebook readers don't support this feat,because audio books, and video books are very CPU intensive.
   Try reading text-based books preferably. Picture based books second. And Audio/video based books last, if you want to save battery.
   
6. Unplug/disconnect as much hardware and software as possible
   Unplugging things like headphones, cameras, and disabling background services that are not necessary (like other tabs with programs running, Whispersync, and other company related feedback settings).
   
7. Disable dictionaries, underlining of popular texts
   You could further save a few seconds of battery life, by disabling the dictionary, and disabling the feat of seeing popular marked sentences in books.
   Generally this does almost nothing, however, sometimes when marking text on screen, the dictionary loads up; which can be prevented.
   

I'm sure there are more things

1. Buy a new reader
   Turning of wifi is all well and good. But once you start disabling SD cards, touch screen and dictionaries, perhaps it's time to put that horse out to pasture.