Power supply calculations to use with Gecko????

[Apples]

I have two stepper motors one is 3.75v @ 2.8amps and the other is 2.7v @ 6amps. I am running gecko's. They say 4 to 25 times the voltage required. so at a minimum I need 15volts, and a maximum of 67volts.

Now from what I understand I have to add my amperage together so 2.8amps+6amps=8.8amps (plus add 2.8amps, for another motor later on for z axis). So, 8.8amps + 2.8amps=11.6 amps, call it 12amps needed.

Therefore I need a power supply that is between;

15volts and 67.5volts and 12amps.

But according to Gecko's, they say that their Geckodrives will only draw a max current of 2/3 of the motors rated amps. So, 2.8amps by 2/3=roughly 2amps (then x2 because we have two motors, z axis will be bought later), and 6amps by 2/3 = 4amps.

So we have 2 amps+2 amps + 4 amps= 8 amps

So does this mean that I only need to use a power supply of 8amps, between 15volts and 67.5 volts?????

Cheers

Peter

[Runner4404spd]

no you need to run the larger power supply. the 2/3 rules is a crude way of saying that all motors will not draw the full power in every situation. if it were me i would probably run a 20 amp supply just to have everything i needed. you need to individually fuse the geckos anyway.

[ger21]

Originally Posted by Runner4404spd the 2/3 rules is a crude way of saying that all motors will not draw the full power in every situation.

According to Mariss at Gecko, the 2/3 is the most the motors will ever draw. Most of the time it will be less. So yes, 8 amps is all you need. But, I'd give myself a little headroom, and shoot for 10 amps. Maybe even more to allow for future upgrades.

The higher the voltage, the hotter you're motors will run. Ideally, you want to use the least amount of voltage that will give you your desired performance. Unfortunately, that can be hard to determine. 15-20x might be enough, or even less.