Battery for stepper motors and controller

Question

Hi to all. The scenario is the following: by one side there is a couple of stepper motors (running on 4.5 Vcc.) and by the other there is the 5 Vcc needed to power the controller board (consuming very few current, i.e. 150 mA). So, there will be two different power lines. To get them from a single battery (e.g. 2A LiIon rechargeable battery), is it sufficient splitting the battery power supply, one to the motors and one to a 5V power regulator to power the controller?

Thank you in advance Enrico

shabaz · Accepted Answer

Hi balearicdynamics That's a very great idea for batteries!! : ) I've not thought about using camera batteries before. How do you connect to it, pogo pin type solution, or 3D-print some holder for it? The 7805 should work fine I think, provided cell voltage under load is around 7V or more for a reasonable length of time for your use-case (I'm guessing it will be).

shabaz · Answer

Hi Enrico! That does work, but sometimes people do have issues with it because of noise or volt drop. Motor power varies a lot too since they are so diverse. An electrolytic cap very close to the motors will help during the motor stepping. Also a 100nF capacitor in parallel there. Plus, separate wires from as close to the battery as possible to the motor circuitry, and separate to the microcontroller circuitry. Finally, loop the supply wires close to the circuitries a few times with ferrite to present an impedance to high frequency noise. You can see similar techniques used in the Infineon DC motor control shield, which uses a large electrolytic across the H-bridge. The XMP-2 design here ran on 6xAAA batteries in a similar method as you describe.

shabaz · Answer

Hi Enrico, If you're using low-power motors then you don't need to have opto-isolation. Even on higher power circuits, opto-isolation is an option (a good option), but there can be other ways too. Depends on how much ruggedness you want to fault conditions, but other ways can be rugged too. For example the Infineon motor control board uses an automotive part (with protection for some fault scenarios), and it is directly controlled by the Arduino (through 10k resistors for current limiting).

shabaz · Answer

I didn't have a schematic for the XMP-2 supply section, but I've added some more detail at that page showing close-up photos of it - not a lot to it, just the DC-DC converter mentioned earlier and a few bits and pieces.

Battery for stepper motors and controller

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