How do I determine power requirements for an 18 towerpro mg955 servo hexapod?

I recently bought a Chinese made hexapod and 32 servo Torobot controller.  Hooking up the bluetooth module to the controller was easy, and so was connecting all 18 hexapod servos, and the programming looks straightforward.

the servos are towerpro mg955.  I have found various info on these (including comments re their quality) but was not able to find out anything about how much current they can use/need under load

I am not worried about the power supply for the servo controller (which works fine), but the 6v 2a supply (wall wart) I am using for the servos seems to be inadequate (servos become spastic/disfunctional when I try to connect and move more than 6 or 7 servos).  that tells me I need more power for the servos.

does anyone know how much current one of these servos uses under load?

also, what battery would I use once I want the hexapod to run without connecting to a wall power supply?

any help appreciated (and sorry if this should be in the newbie forum)

** **


pic of the robot

here is a pic of the robot on ebay.  shows you details on the legs etc.

according to

according to this

these servos consume in 4,v 350mA ,so the best thing is use in 5v what give us 365mA

0,365mA*7(quantity you choose)=2,5A