Project with stepper motor (alimentation questions)

Hi everyone :slight_smile: ,

I am a perfect noob at this so would like to some confirmation before I start buying all I need.

I would like to power a stepper (this one: http://vslot-europe.com/home/45-high-torque-nema-17-stepper-motor.html)

I have chosen the following driver: http://www.robotshop.com/eu/fr/controleur-moteurs-v2-arduino.html

Then I also would like to power the driver using a battery. I have found this: http://www.robotshop.com/eu/en/dfrobot-7-4v-lipo-2200mah-battery.html

Questions:
1/ Is there a problem using those elements together ? How to improve?
2/ If I power the driver, will I still need to power the arduino or do I need a small battery for the Arduino (I use an Arduino Uno btw)

Thank in advance for your help ;D ;D ;D

I would highly recommend a battery charger with a long cord to charge the battery every few minutes as it kills the battery.

That battery is just perfect to power the Arduino for a day.
Now find a mucho bigger one to power the motor.
Leo..

I think that shield uses an L298 for motor control - that is a very poor choice for driving a stepper motor. You should use a specialized stepper driver. Your motor needs 1.5 amps so I suggest you use a Pololu DRV8825 or equivalent.

See stepper motor basics

Stepper motors require their full current all of the time, including when stationary which makes them very inefficient. You will need a large battery.

Also, your motor will perform better with a higher voltage - 12v or 24v (and, of course, a specialized stepper driver)

...R

there are carts, and there are horses.....

on this project, it seems there are a few carts and no horses.

before anyone can recommend anything,
before any selection of parts or circuits.

you need to figure out what you are doing.

you have a perfect XY problem here, you want us to offer specific answers to parts that you selected, but we are not aware of the APPLICATION.

as you can see Robin2 does not like the L298, in some APPLICATIONS, it is the perfect choice, in others, it could not be more wrong. that can be said about relays, or even an arduino.

the APPLICATION drives the parts selection.

tell us what you want to do.

a stepper is only good to half step. it will fall naturally to a full step when no power is applied.

at very slow speeds, a stepper motor will cog and clunk and rattle, WHEN run in a full step mode.
at high speed, the motor will run fine on full steps.

the choice of a stepper driver is, or should be based on the application.

if you have the driver already, great, you can use that.

the L298 is part of a chip pair. the L298 is the driver module. the Arduino is replacing the step/direction chip and therefore you need to feed it with 4 pins of the Arduino. you can use the code from the driver supplier and have that portion solved easily.

the A4988 chip that Robin2 recommends has the ability to micro-step or turn each actual step in to a controlled ramp of power to each coil to make it work. the A4988 will not give the stepper any more power than the L298,
this is a cart, without a horse.

about voltages, a stepper motor can work with higher voltages. the simple formula is that power increases with voltage.
so, if you need more power than you are getting, then increase the voltage instead of getting a new motor.
but, I think you are not there yet, so that cart is also without horse.

if you take away one thing, I hope it is that the APPLICATION drives the parts selection.

Thank you all for your quick replies.

Indeed I understand I should have specified the application :slight_smile:

I am doing a 1.5 meter slider.

I have found this video. And this is exaclty the same thing I am trying to do: Building A Motorised Camera Slider Using V-Slot Acessories - YouTube

estadieup:
Thank you all for your quick replies.
…SNIP…

I am assuming you have no further questions for the moment

…R

for that, I would recommend the A3988 that robin2 mentioned.

Actually I do have some questions for you :slight_smile:

I have just seen that Lipo might not be the best way to power the stepper. NiMh could be simpler to use.

Question 1: Is it a good idea to use NiMh since the weight is not a problem to me?

I have found 2 batteries:

Dumb Question 2: If I buy 2 batteries (6V, 2100mAh), and that I wire them in series, I would have a 12V 2100mAh battery for the price of the 12V 1600mAh battery.
Is there a downside if I do so?

Thank you again for your help !

The cart is still before the horse.

First build the slider, and determine how much force/torque it will require in operation.

Then use that information to decide on a motor and a power supply.

estadieup:
Dumb Question 2: If I buy 2 batteries (6V, 2100mAh), and that I wire them in series, I would have a 12V 2100mAh battery for the price of the 12V 1600mAh battery.
Is there a downside if I do so?

The pair of 6v batteries would work as you say, with no downside.

The motor you have mentioned probably requires more than 4.5 * 1.5 = 6.8 watts - say 10 watts. The 12v battery would need to deliver 0.8 amps to deliver 10 watts - say 1 amp allowing for losses. The sticker capacity of batteries is usually hopelessly optimistic. So at a very rough guess it might drive the motor for about an hour. Some of these numbers have a large margin of error. And they assume an efficient stepper driver - not an L298.

I agree with @jremington. When you build and test your slider you may find you can get by with a much less power hungry motor, or you may need even more torque. But perhaps you have already bought the motor.

…R

Thank you everyone for your help.

Indeed I have bought the stepper. This stepper was recommanded for this application.

I have also built the slider (I just need to fix the electronic now).

I think I have the information I needed to carry on :slight_smile:

Thank you Robin for your help and your link (that I have found very usefull).

Thank you dave-in-nj for giving me some insight into the stepper and its driver.

Thank you jremington and Wawa !

So now @Robin2 you might assume I have no further question :slight_smile:

estadieup:
So now @Robin2 you might assume I have no further question :slight_smile:

Come back when / if you have.

...R