Does the iPhone battery lose power over time?

[shetland]

Hallo, I want to know if the iPhone battery loses power over time? Does it lose power the more you use it?

 

[MATLABdude]

The Battery University has a page that you might find interesting:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

In a nutshell, lithium ion batteries have a finite number of charge cycles, and the amount of charge they hold (and consequently, your run time) decreases as its charge cycles are used up (as seen in their Figure 1). However, additional factors--like the actual age of the batteries, power draw, and temperature they're held at, as well as the charge state when batteries are left for a long time--will also impact how much capacity they have.

Apple claims that their iPad / iWhatever age more "gracefully" than other competitors, but as far as I know, they use the same cells that everybody else is using (caveat: I haven't looked up whether or not anybody's performed aging tests and quantified results as in the article above). Given that I charge my 2.5 year old iPhone 3GS every night, and don't really run it down too far every day, I'm probably due for a battery replacement pretty soon.

 

[Greg Bernhardt]

I'm probably due for a battery replacement pretty soon.

Which you must send into Apple and it's expensive right?

 

[MATLABdude]

Which you must send into Apple and it's expensive right?

All you need is an out-of-warranty phone / pod / pad, steady hands, some parts (pay for the real deal), and a cheat sheet!
http://www.ifixit.com/Device/iPhone

Apple actually does have some battery-replacement while it's under warranty (including the extended two years of AppleCare--totally worth it if you have the educational discount):
http://www.apple.com/batteries/replacements.html

EDIT: You should probably also have the ballsiness (or female equivalent thereof) to risk operate on a $500ish device.