Originally Posted by tompe
Yes, but it will loose capacity even if you do not use it. So the important factor is if keeping it always on really will decrease the capacity significantly faster. I doubt it.
I think it actually will.
There are two factors which "age" a Lithium Ion battery:
1. A "natural" decay, which starts the first time it's charged. Typically a LiIon battery has a "lifetime" of perhaps 5-7 years.
2. A "charge cycle" decay. As well as its "natural" lifetime, the battery will lose a small amount of charge capacity for each charge cycle it goes through.
Item 1 will not be affected by leaving the CyBook turned on, but item 2 will, because you'll be charging it more often. After a year or two, a Cybook that's permanently turned on, and charged once a week, will almost certainly have a lower battery capacity than one that's turned off every night, and hence only goes through a charge cycle once a month.