Hello, I've searched for this issue but all I can find is information on battery capacity issues and advice on how to correctly charge your iPhone, but nothing on this problem... I received my iPhone 3GS 16GB last Tuesday. After registering it, I attached it to my laptop so that I could unbrick it on iTunes. I allowed it enough time to achieve a 100% battery charge and then unplugged it and went to bed. The next day I had some network issues connecting to the aps store so I decided to power my phone off & on. I'd been using it a little during the day so the battery was around 52%. I powered the phone down, left it off for around 3 minutes, then powered in on again. As soon as it powered on it gave me the 'below 20%' battery warning... and then about 20 seconds later it shot back up to 47% and seemed to be fine. I put this down a quirk, but this hadn't resolved my problem connecting to the aps store, so I then reset my network settings. As part of the process the phone rebooted itself to restore the settings. Once again, after the reboot, it gave me the 'below 20%' warning and then shot back up to 40 odd percent again. I do know a lot of people with the iPhone so I asked them if this was normal (I asked around 10 people) and almost all of them said no it never ever happens to them, but one person did say he has the same problem. He's had his for months and it's always happened, but he's had no other issues so he just puts up with it. I called Apple to ask about this problem and they never heard of it, but suggested I complete 4 full charging cycles from flat to full before I report it as an issue. I've now done this and I still have exactly the same problem. when my iPhone is off/on it always reports a lower battery level than it actually has, and then this shoots back up. Now, I don't plan on turning my phone off and on much anyhow, I've only been doing so to monitor this problem and see if it's still happening. Well it is still happening, but I could actually put up with it if I knew it was a minor glitch and didn't impact the phone in any other way. Seeing as I know at least one other person with the same problem, I figure that despite what Apple say, there must be more people out there who have or at least know someone who has had this issue. Does anyone have any information on how this could affect my phone long-term, if there's any fix (full-cycle charging doesn't fix it!), or any rock solid info on this being a fault? I'd appreciate any thoughts on this 'cos I'm pretty much clueless!