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I've two step motors with 12V-0.4A each, A4988 as stepper motor driver and CNC shield on Arduino. As I know I should use at least 2x voltage for stepper motors and I would like to know, if I use 24V-4.5A power supply, can it lead to any problem with these devices?

Or should I use something equal to needed current? (2*0.4A + cnc shield etc. let's say 1A for example...)

she hates me
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The current rating of the power supply is not important, if the minimum requirements are fulfilled.

The current is determined by the output voltage and the impedance of your load. When a power supply is rated for up to 4.5A then this is the maximum that this power supply is capable of. It does NOT mean, that the power supply is always outputting this current. So, also your load might only need 2 x 0.4A, a 4.5A power supply will do no harm to your devices (because there will be only a current flow of these 0.8A).

But I'm not sure why you think you would need double the rated voltage. A voltage exceeding the ratings of your devices WILL damage something!

jusaca
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  • thank you very much. I thought 2x0.4 A because I use two motors and each one needs 0.4A. Shouldn't I multiply it with 2? – she hates me Apr 01 '19 at 09:07
  • Yes, you need double the current ( 2x 0.4A = 0.8A). But not 2x the voltage! – jusaca Apr 01 '19 at 11:48
  • I read bipolar stepper motors are driven by the current and they work better with at least 2x voltage, my motors are 30 ohm and 0.40A, so 12V and thats why i chose 24V supply. Do you think it makes sense? Or am i missing a point? – she hates me Apr 02 '19 at 03:25