Well, I am making a 4 legged robot, this one https://www.robotshop.com/letsmakerobots/node/31902. I have already written the code for moving forward, even that I am still expecting some parts. The code works well, the servos are moving well, but just with the power source by the computer, via the cable USB. When I put a battery, it doesn't work at all. Could you suggest something that couldn't work well?? I checked the connections, they are all well. The battery is 9V and there are 12 servos branched at the Arduino UNO.
A 9V battery does not have
A 9V battery does not have enough current to run the servos. Use a different 6V (max) battery for them and they will work.
I’ve had some great help
I’ve had some great help with a similar problem in this topic: https://www.robotshop.com/letsmakerobots/node/31945
As Ro-Bot-X said, A typical 9v battery doesn’t have enough current to power your servos. You’ll want a battery(pack) with a couple 1000Mah. So a bunch of Ni-Mh AAs or a Lipo battery will probably do. I guess best would be to check how much current each servo needs and then get a battery that will be able to cover all 12.