[Timboli]

There are some batteries now of course, that keep their charge for many months. My Samsung Tablet has those. Unlike my two Kindles who lose their charge quickly, especially the Kindle Keyboard, which is a bit old in the tooth these days. Neither of the two seem to last much longer than a fortnight to a month when not in use. Of course, if you constantly or regularly charge the device, you probably wouldn't notice the depletion very often.

If you don't turn a device fully off, then a trickle charge maintains things in RAM so it can quickly turn on. It also uses a very small amount to keep the screensaver showing on E-Ink Kindles.