Stepper motor voltage & Driver question

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animal
Posts: 29
Joined: Sat May 06, 2017 11:03 pm

Stepper motor voltage & Driver question

Post by animal » Sun Oct 29, 2017 3:15 am

hi there , I have a few questions . when I bought my CNC shield 3.00 it came with A4988 driver's & see a lot of projects using DRV8825 . I am using Powermax11 steppers , is one driver better than the other? or should I stick with the A4988's? My steppers sa that they are rated for 65 VDC ,do I loose anything running them at 12 or 24 VDC? Does the amp draw go up with the lower voltage ?
tks
animal

gmoney484
Posts: 135
Joined: Wed Nov 09, 2016 8:52 pm

Re: Stepper motor voltage & Driver question

Post by gmoney484 » Sun Oct 29, 2017 4:56 am

The 8825 drivers allow a slightly higher current than the 4988's - the difference is almost negligible - maybe 10% higher. There is a big current jump going to external drivers like 6560s or 6600s - and they aren't a whole lot more expensive, but they take up more space and require more cabling and possibly external power.

The limit of a stepper and driver is the current. The current is determined by the voltage of your power supply and the resistance of your stepper (which is kind of constant) - V=IR .

If you use less voltage, you get less current (and less torque and stepping speed). So it's safe to decrease the voltage, but inefficient.

If you increase the voltage, you get more current - until you supply more voltage than your rated stepper and you fry your coils in your motor.

So as you increase the voltage, you will increase the current. Both drivers 4988 and 8825, shut down if they get too hot (because of too much current). Which happens pretty easily and is annoying (because it will lose steps). There is a potentiometer on the driver to limit the maximum voltage and hence current. So generally, the limit is the maximum current of your driver (before it overheats and shuts down). Effectively, you can't supply too much voltage (to a well adjusted driver).

Without going into details however, the more voltage generally gives you more torque and faster stepping. High voltage is best. External drivers are best too (they also use bigger heat sinks so dissipate heat better)
Gavin Milne
HoD Science
Dilworth School

tingzhiou2
Posts: 1
Joined: Fri Nov 22, 2019 8:28 am

Re: Stepper motor voltage & Driver question

Post by tingzhiou2 » Mon Nov 25, 2019 8:09 am

hello, i have similar problem as you. But it is still not be solved.
I just got 2 stepper motor and driver.
I have ask the oyostepper.com customer service. But they also can't help me.

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