So nobody can suggest a good power source for this little thing? Please this is my first robot and I can't even run it disconnected from my PC. I tried a 9v and it didn't do anything then I tried 4 AA's and those seem to power the robot but I think its getting low power because the wheels only want to turn right for some reason. I know the code is fine because when I plug in the usb to the arduino and PC everything works perfect.