Hi
I’m no authority in the subject, but it’s just my personal experience with new batteries… especially with these devices.
Taking, per example, the information from one of the eBook reader makers - Irex , producers of the Iliad and the DR 1000S (
http://www.irextechnologies.com/batteries):
“Battery-lifespan
A lithium-ion battery like the ones used in iRex’ products can deliver its maximum battery-life for a long time. After 400 charge-cycles the battery should still be able to achieve 80% of the maximum battery-life. Temperature can also influence the battery-lifespan, therefore it is best to use your device at temperatures between 0º and 35ºC (or 32º to 95ºF). The best storage temperature for products with a lithium-ion battery is room temperature. Heat, for example in a hot car, can strongly degrade the battery's performance and lifespan.”
Let me say one more thing, I do have a Cybook who completes now 18.5 months of age with normal reading use, sometimes one book per day, sometimes one to two books per week, and the battery is still perfectly strong.
Never recharged it bellow 40% and normally when its’ around 70%, plus the normal connecting to copy content to the reader or delete from it (so t charges that “bit”).
Once more, my advice is forget about it, it’s the first device one can forget about battery use and or death (besides normal malfunction ones, that no one can predict).
Enjoy your reader,