Don't say sealed battery

[Cigar-Junkie]

Does anyone know what the average life-cycle for an Iphone battery and how much it normally costs to replace?

I'm asking because I know phones can become dated and it's unrealistic for most to keep the same phone for years unless you are really only looking to call or text, but I still like the idea that my old phones may still be useful in a few years as MP3 players, mini-wifi tablets, and even backup phones.

I am assuming that any device with a sealed battery will eventually lose the ability to hold a charge. Is it even worse if that device is only charged on random days when needed and not on a regular basis as a normal smartphone would be.

Does anyone know of anybody using the original an original Iphone that is still going strong? They sell them on Ebay, so I am assuming the sealed batteries may have a long life, but nothing lasts forever.

As I have been looking into this because I am getting a new phone soon Galaxy Nexus or iphone. Also because two of my kids have iphones and these two things came up.

Most batteries are affected by "charging cycles" but I noticed that my kids plug thier iphones in about two or three times a week. I plug my DX in several times a day.

In looking at the new iphone 4S the standby time is 200 hrs. Internet use is 6 hrs.3G and 9 WiFi I see where in the sealed battery discussion the talk is to have larger battery like the iphone. The spec I was able to find was that the iphone has a 1420mAh battery. My Bionic extended battery was 2760mAh and still fell badly short of a full day. I also didn't like the added bulk in the phone and went back to battery swapping before I returned it.