IPhone 3GS Charging while Docked
I have docked my iPhone 3GS in several different docks (2008 BMW, Yamaha iPod dock, etc.) In every case the phone displays a message that the external device does not support charging, and do I want to switch to airplane mode to conserve power. At the Apple store I was told that the new iPhones use different pins for the external power, and that a $20 adapter was required to support existing docks. I bought one, but it seems to have no effect whatever. Is it possible to charge the 3GS while docked? If so, how?
Since both the docks and the USB cable that comes with the phone use the same plug on the bottom of the iPhone, does that mean that the adapter sold at the Apple Store should indeed take the dock's power from the Firewire pins and reroute it to the pins used by the USB connector? In other words, is it possible for an adapter to allow an existing dock to charge a new iPhone?
If this is what the adaptor is advertised and sold to be used for, then yes. This should allow for charging via USB, but it probably won't prevent the warning or error message from being provided if the device your iPhone is connected to with the adaptor does not include the "made for iPhone" certification.