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Originally Posted by J.C.
The device doesn't turn itself off after every page load ...
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The device doesn't turn itself off as such. This was a simplification. But the processor does go to the "idle" state and waits for one of buttons to be pressed or for G-sensor. One of first devices Iliad from iRex was unable to turn processor to idle state and the result was that the battery only lasted fraction of the time they promised.
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Originally Posted by J.C.
When a user presses a button he knows power was used by the change in the display, same goes for using the g-sensor to change the page orientation.
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Sometimes, when you have G-sensor activated even a small change in position results in processor "waking" from idle state, without actually changing orientation.
Page turn isn't the only situation when processor is working. There are situations when the LED is on for a long time. For example when you have changed the font size or when you have opened the book and the device is repaginating the book.
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Originally Posted by J.C.
That LED absolutely does not indicate that the device is working,
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Yes it does.
It indicates that the processor is eating maximum level of power instead of much lower "idle" consumption
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Originally Posted by J.C.
Give it some thought ... do you really need to see the led turns on when you can see on the actual display if the action you made resulted in a reaction?
Do you really need a constant reminder every time you turn a page ... that the drawing of a new page takes power?
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I *have* given it some thought.
This is a design feature. There are arguments against - such as your last point, that the LED itself eats power - and there are arguments in favour of this feature.
Sony reader or Kindle do not have such LED and people are obviously using those devices happily.
When I was using Sony PRS-500, the device could eat through *lots* of battery juice in very short time when re-paginating long book or when I have loaded an SD card with many books that the device started to index.
Kindle users have the same problem. Some people load lots of books in one go and the device starts to index the books (for the built-in search function) and the battery goes down very fast.
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Originally Posted by J.C.
Is it that constant reminder that power was used so important to you ... that you need to used more power by turning on a LED ?!
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Yes, I *personaly* prefer to know when the power is drawn. But I wish they used something more energy efficient than that power-drawing LED ;-)
A good low-power LED has power consumption of 2mA [miliAmper] at 1.9V. The battery can provide 2mA at 3.7V for 500 hours. So ... the battery could power the LED for 35 days of continuous light (using step-down converter with 90% effectiveness)