Yesterday, I charged my iPhone3G from "10%" until completely full using my car charger. No problems at all. Today, I was on a "mini road trip," and I was using my GPS, yet even though I had it plugged in, the battery kept getting lower and lower, and then the "20%" and then "10%" warnings popped up. Upon seeing 10%, I looked more closely, and noticed that instead of the usual "lightning bolt" in the battery indicator, it had an image of the power plug but the battery was at 10% and not full. I disconnected my phone and then reconnected it several times. Nothing. Then I exited the GPS application and turned "location services" to off, and WHAALAA!!!, my phone began charging. About 30min later, I turned Google Maps back on but kept the location/GPS off. My phone kept charging. As soon as I clicked on the bottom left corner for the GPS and it asked me if it was "OK" and I tapped "OK," I then noticed the battery stop charging. I'm guessing that the GPS is such a battery drain, that trying to charge at the same time could harm the battery, and so the iPhone is programmed to not charge when the GPS and 3G are both running. Anyone else have a similar experience?