I would like to know if the 9V battery would draw enough current to properly light them up.
In my scetch I may want to light only few of them at the time but in rare cases I might want to have them all light up.
Not sure How much current a single LED needs and do I multiply it by 8 to get the total of current needed.
If 9v battery is not the way to go what other options do I have . I need this to be mobile so it cannot be connected to wall power supply
The WS2811 chip is supposed to be run from 5V. (It can drive 3 LEDs in series with 12V supplied to the LEDs while the chip runs from 5V.)
In case you don't know this, they are not regular RGB LEDs. The are addressable and controlled with serial data which requires a software library. has all of the information you need and they also have a library you can download.
Not sure How much current a single LED needs and do I multiply it by 8 to get the total of current needed.
Right! About 20mA per color X 3 colors X 8 = 480mA.