After about 400 full cycles, the battery is expected charge to 80% of its original capacity. It should be quite clear 80% is not zero. Furthermore, this is a gradual reduction.

So, currently the battery provides about 8 hours talk time, about twice that of the 4 to 5 hours of other phone. After about 400 full discharge cycles one could expect about 6.4 hours, which is still more than other phones. Also keep in mind other phones use similar batteries, and their 4 hours of talk time would be reduced to about 3.2 hours at that point.

Let’s keep this in perspective.

Supposedly and according to Apple, each charge cycle does not count as full cycle unless it’s fully depleted but is a sum of the partials. Speaking of full depletion, it’s not good to leave any Lithium battery depleted for any time and it’s best not to store one fully charged either.

See http://www.apple.com/batteries/notebooks.html and/or http://www.apple.com/batteries/ipods.html for good info. I would add to the part about storage that you should store it in a refrigerator (NOT freezer–use for alkalines only). I did that with my extra battery for my 2001 iBook and it still has excellent life.

Make sure to warm it to optimal temp before using.

Lastly, I suggest doing a google search on lithium battery care and pay attention to who is saying it. Trust entities that work with the technology before trusting a site that does not.