So it seems that two of the pins in most USB chargers aren’t compatible with the iPhone because they are missing D+ and D- pins and because Apple engineers hate us all. This little project describes how to make your own or hack your old USB chargers to support the iPhone. N.B.: Do not attempt if you are me because you (I) will inevitably blow something up.

I have tons of USB car chargers lying around because it seems like every device that I buy comes with one free. These chargers are very simple in construction. They take in 12V and they output a regulated 5V to the USB ports. These cheap chargers will not work with the iPhone because the D+ and D- pins are not connected. I can remember at least one incident when I need to charge my iPhone but couldn’t because I didn’t have the proper car charger.

via Make