Originally Posted by SameerH
Slap some conservatism on there (say 60%) and you're left with 3 years to get down to 80% retentive capacity.
That's really not bad at all. I still think Kobo should have some kind of battery replacement program, hell you could even charge some amount for it and make the customer pay shipping. Still better than buying a new device.
Batteries are fickle and very greatly depending on the user's habits. Many people don't know how to use a device properly to maximize the lifespan of the battery.