iPhone 3G[S] not charging on usb port in car

[topherg]

The firewire/usb pins are at the dock connector end of the cable, not the usb plug end. So, if the OP is using the cable that came with his phone it should work with any USB charger (provided it's putting out the required wattage) because the cable will definitely have the correct pinouts. The firewire/usb pinout problem was only for accessories like docks, speakers, very old cables etc. that had a dock connector with the wrong power pinouts built in.

None of this explains why his car would charge his 3G but not his 3GS - both these phones use the USB charging pinouts.

Unless the 3GS requires more wattage to charge than the 3G I dont see any other explanation for my issue....

 

[Hoodah]

I'm having a similar issue. I think it boils down to the fact that the 3GS won't start charging unless it detects a data connection (via usb) as well as the correct power voltage. My old usb car charger adapter only supplies voltage to the usb power, not data, for obvious reasons. But the iPhone won't accept the juice.
http://eirikso.com/2008/08/07/update-on-the-usb-charging-problem-of-the-iphone-3g/

 

[HashamSyed]

Here is a solution to the problem

http://www.tzywen.com/modules.php?name=News&file=article&sid=683