Why is the iPhone 3G not compatible with previous car adapters? I was using the original iPhone with an adapter that allowed me to connect to the radio through the CD Changer input. The new iPhone 3G audio portion works, but will not charge the battery like the previous iPhone did. It charges the battery with a regular lighter charger.
Apparently Apple changed the circuitry inside the newer iPhone 3G and because of this most older car chargers that worked on the original iPhone will not work on the iPhone 3G. Many have said that the Griffin PowerJolt will work on the 3G iPhone both the regular PowerJolt and also the PowerJolt SE. You can find these online for about 13 bucks. These adaptors have not been branded officially for the iPhone 3G but they are known to work.
There’s a good discussion here about at the MacRumors Forums.
Thanks,
What they did is they stopped using the power over firewire pins and now the iPhone only accepts power though the power over USB pins. They did this to simplify the amount of circuitry required in the device.
Regards,
Luis