Push the PlayStation button in the middle of the controller to turn it on. Wait for the lights on the controller to stop flashing. Once the lights have stopped flashing, unplug the mini USB cable from the controller. Your PS3 controller is now ready to use.

Why does my PS3 controller not turn on?

If the controller won’t turn on at all, the problem likely lies with the battery or the internal hardware. First, try removing the battery and re-inserting it: Use an eyeglass repair kit to unscrew the back of the PS3 controller. Re-insert the battery and try turning on the controller again.

How do I know if my PS3 controller is working?

With the controller connected to the system, a controller number is automatically assigned to your controller. A solid red light appears next to the port number on your controller. Press the buttons on your controller to test your device. If the buttons work, continue with normal use.

From my experience it can take about 15 to 20 minutes, from completely dead to fully charge but as Lunar Chaos had said it can also depend on how long you have used the controller.