8825 driver versus st-6600 driver

I have many of the pololu 8825 drivers. I have the heat sink mounted and have air being blown on them. According to the spec sheet I can put 2.2amps PER PHASE through them or 4.4amps total for a typical 2 phase stepper motor.

I have purchased the ST-6600 from stepper online. It has a rating of 4amps per phase (5amps unrated).

http://www.omc-stepperonline.com/bipolar-stepper-motor-driver-max-4a-current-40vdc-input-16-subdivision-st6600-p-246.html

It has a large cooling fin and barely gets warm when I set the switches to a full 4amp.


1) Am I correct in my assumptions that pololu is 4.4amps total and st-6600 has at 8amps total current?

I just want to make sure I am not damaging my motors while at the same time pushing through as much amperage as possible for increased holding power.

Thanks.

The motors should be hot when working near capacity. Too hot to touch. If they are smoking then tell them that's a cancer risk and dial the current down a little. Forced-air cooling on the motors will work too.

Thanks Morgan.

Just one more question.

Increase voltage to the driver increases the max speed of stepper.

But does increasing voltage also increase the holding torque?

DivinerGregg: But does increasing voltage also increase the holding torque?

No. I am assuming you have the current limit set correctly to protect your motor.

The effect of using a higher voltage is to get up to the max current more quickly so as to maintain the magnetic force in the face of the increasing inductance and impedance at higher speeds.

...R

The 2.2A limit is not per-phase, these drivers are sinusoidal quadrature, the limit is for the amplitude of the current phasor.