Could the current passing through my Arduino voltage regulator fry it?
Do I need to build a separated circuit for the motors?
These motors are driven by two Pololus A4988 at 1A 9V each.For the moment I am using a 12V battery at 2.9Ah with two voltage regulators but I will probably remove them and replace my current battery with a 9V at about 6Ah.
As others have said don't try to power the motors THROUGH the Arduino. You should not have any problem powering the Arduino from the 12v supply.
Stick 12V direct into the the A4988 drivers.
A 6Ah battery won't last long with 2 motors each drawing about 2 amps continuously.
The A4988 will pull a lot less than 2A from the supply, note, they power-convert so the ingoingcurrent is less than the motor current.
I agree that using steppers for robot traction is about the worst way you could do it. StandardDC motors, wheel encoders, that's how you get battery life.
I can't, my motors must be powered at 9V.Each motor draws 1 Amp, not 2, so it would last for about a little less than 3 hours.
So basically I don't need a battery that large?