Originally Posted by HarryT
Regardless of charge cycles, lithium batteries do degrade over time. The clock starts "ticking" the first time the battery is charged, and there's no way it can be stopped. You could reasonably expect a good quality lithium polymer battery to have lost perhaps a third to a half of its original capacity after 3 years.
Charge life of the battery is probably not why we replace the eReader. I just purchased my Sony PRS 900 with case in December, 2009, for $ 400 and now, in my opinion, the Kindle 3 LG WiFi with case goes for $ 180 and probably beats the Sony for portablity and readability.
I had purchased a Sony PRS 505 just 10 months prior to the PRS 900.
I expect that by the end of 2011, I'll be dumping the Kindle 3 to buy another eReader - brand still undetermined.
Thus, battery life is IRRELEVANT. Obsolescence causes all electronic gadgets to be dumped for GPS devices, PC's, cell phones and eReaders.
If not for obsolesence, I'd still be using my Radio Shack TRS-80 16 Kb with DOS 1.0 8 bit from 1979 instead of my Dell Minitower XPS 7100 1.5 Tb with Windows 7 64 bit.
The 500 charge limit was stated in my NowBible manual which also uses a high grade lithium polymer battery and EXPRESSLY stated that information. I use that one daily with a dramatized sound broadcast of the Bible over one year. I use that battery until it runs totally dead. I get 22 days using it that way until the charge is required. I do recharge it weekly if I have a Bible Study to attend that week. I've been using that device since 3/22/2010 to the present and have recharged it only 14 times. If I have to charge it at that rate, it will average about 30 times per year. It could last over 10 years at that rate. However, it will also be OBSOLETE in about 12 to 24 months.