Dualshock 3 flashing lights but won't stay on! Can you please help?

So, I don't have my PS3 around, so I thought I could make my Dualshock3 my new PC controller, to play games like FIFA and so on. Today I tried to turn the controller on, and nothing... I pressed the reset button and then I pressed the Playstation button ( you know that little Sony button nearby the analogs) and th lights flashed for like half a second but it wont stay on. I wanted to know if I have to open it up or is there a easier way to fix this? (Remember its only connected to my PC not to the PS3, so I can't charge it on the Playstation)