Answer to: iPhone 3G won't charge with either the usb cable or wall charger.hello, as described, put 5v from usb directly 2 iphone battery is not a god idea yayaya, due to voltage and current total different. the battery schematics up is wrong, in fact the polarity is inverted. 1st pin is vcc and the 4th is GND. the 2 and 3 pins are correct. now, for check if battery works, try 2 charge as standard nokia bl5C battery. connect the right polarity to a standard nokia phone, then put a 5k resistor between the 2nd and 3rd pin of iphone battery, then connect the 3rd pin to central pin of nokia's mobile. connect the phone into a wall charger and see what happens. good work.