I had an iPhone 4S from launch day with a S/N starting with D, the battery was terrible. I was lucky if I got 1hr 30mins usage and a 1.5 days standby. I took the phone to the genius bar on the 1st Nov, he tested it and said the battery was fine, he showed me the results. They said at the last charge I had gotten over 5hrs usage and over 2 days standby and I had 89% left when I plugged it in, now with those figures I would have been overjoyed.
Unfortunately the test results weren't correct, the last charge I had actually only got 1hr 30mins usage and just over 1 days standby, the phone turned off at 1%. Then he noticed my phone had never made a phone call according to the test software, this was incorrect as the phone itself was showing several calls had been made. The Genius's conclusion was that something was seriously wrong with the 4S, but the battery was fine!!, he changed the phone. The new iPhone 4S serial starts with a C.
Now it's 12th Nov and the battery is what the first phone should have been, it received a full charge on the first night, and I am now averaging 6hrs usage and 2.5 days standby The new phone was restored from the backup of the old phone.
Is there a problem with serial numbers starting with D (doesn't seem to be) or was it a rogue phone, how many other people are being told by Apple there batteries are fine when clearly they aren't, either due to faulty testing software or faulty phones giving incorrect readings on the software, I would think the latter is most likely.
Both iPhones had everything turned on except Bluetooth and location services Setting Time zone,
Is the issue to do with hardware or firmware? From my perspective it's hardware.
If you have a problem with your battery take the phone to an Apple store and get them to check it, ensuring you know your last usage and standby figure, see how these compare with the Genisus's test results.