Although I don't read with the cover on, so I can't speak for long term watching of battery that way, I just put it in while the Oasis had 92% battery. I had just started to read. And the cover has 55%. It right away says kindle (charging from cover). And as I am typing this, it went from 92 to 93. For me the kindle stops around 94 with charging. It never goes to 100 while in the cover for me. I looked at that several times. It does of course go to 100 while both are charged together.
From what I can tell with my limited in cover checking, once its at 94% the kindle will stop charging from cover and then drop down to a certain percentage somewhere in the 80's. But when it starts charging from the cover again, I do not know since I always read outside of the cover.
I read many hours a day, every day. And after just over 6 months I notice zero difference in the charge it holds. Kindle or cover. Exactly the same. So it will be quite a while before I will notice any break down of the battery.
I think its pretty safe to say that by then I will probably have another kindle. Heck, I still have all my kindles from 2008 on and they just wont die. Battery or otherwise. So I trust Amazon's track record on that.
I'll be happy to update at the 1 year mark as a heavy reader. You know, someone that actually uses a Oasis on a daily basis for many books.
Oh and like someone else said. None of that really matters. The bezel on the Voyage is too small for me to comfortably use the haptic buttons without constantly touching the screen. And I have very small hands, which causes me to drop the Voyage out of my hands when I try to do all that with one had. The Oasis is perfect for my hands, has actual buttons and I am reading much much more now with it. So none of this battery talk has any use for me. I must have the Oasis for comfortable reading. That is about all there is too it. If it lasts 2 years, I'll have read 100's and 100's of books on it happily. But looking at my stack of still working fine kindles, I see still having this Oasis great condition even in 2 years. Unless there is something even better coming along, which is hard to imagine. Then I'll add it to my stack of kindles, or pass it down.
