Instructions
Plug the controller into a USB port, either in the PlayStation 3 or another device. The PlayStation 3 must be turned on to charge the controller.
Check the red light on the controller to make sure it is lit and blinking. If it is not, ensure that the USB cable is properly connected to both the controller and the console.
Press and hold the PS button on the controller for about two seconds. If it is properly connected, you will see the charge status on your screen, indicating about how much longer it will need to stay connected to fully charge.
Continue playing the PlayStation 3 while the controller is charging. Once it is fully charged, the light indicator will stop blinking.