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)
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.
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.
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.
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?
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.
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