Your kindle can easily last a couple of weeks at a time and charging a kindle is quite a rare moment. However, we can further extend its battery life just by switching on Airplane Mode. Simply swipe down and tap on the airplane icon. This disconnects the Kindle from the wifi and ceases all downloads and updates.
There is a common misconception that light consumes more power than dark mode. Unless, you are using the brightess setting on light mode, there is neglible difference in battery consumption between light and dark mode.