Phidgets stepper motro RPM

Hi,

First the setup:

• Stepper motor: NEMA-17 Bipolar 99.51:1 Planetary Gearbox Stepper - 3319_1 at Phidgets
• Pololu DRV8825 high current stepper driver: Pololu - DRV8825 Stepper Motor Driver Carrier, High Current (md20a)
• Stepper motor to DRV8825 wires: B2 (blue), B1 (red), A1 (black), A2 (green)
• 12 V Lipo battery pack

This setup works fine for very slow rotations. The maximum RPM I achieve with this is around 0.7 RPM. But I want to rotate the motor faster to certain positions from where it then should then rotate very slowly.

I already tried to double the input voltage using 2 lipo packs in serial and changing the potentiometer on the DRV8825 board. At a certain point on the potentiometer the motor begins to stutter until it finaly completely stops (probably the DRV8825 overheats).

How can I increase the motor speed? What alternative driver could I use which is controlable by Arduino which allows more current.

#define motorSteps 200

Stepper myStepper(motorSteps, pinStep, pinDir); 

void setup() {
  myStepper.setSpeed(300); // maximum working speed
}

void loop() {
  myStepper.step(1000L);
}

Regards,

The rotation speed is a software problem. With the following EasyDriver code I get better RPMs: http://bildr.org/2011/06/easydriver/
So I will skip the Stepper library and write my own stearing code.

If speed is still a problem a higher voltage supply will increase the maximum rate, the DRV8825 chip will take a supply up to 40V or so....

Doesn't the speed depend on the rate of pulses you are sending to the motor ?