Powering Stepper Motor + Uno + Easydriver with Solar Panel + One Battery

I am trying to build an automatic chicken door closer and bought these parts:

I got a NEMA 17 stepper motor here:

http://www.ebay.co.uk/itm/121680099003

EasyDriver:

http://www.ebay.co.uk/itm/A3967-Stepper-Motor-Driver-Controller-EasyDriver-v4-4-Un-Soldered-Arduino-Pi-/252206484022?var=&hash=item3ab8ad8a36:m:m6vlosGKsE25CUGky7onGVQ

And the Arduino Uno.

It cant be mains powered because the chicken coop is outside!

I would like to power this ideally with solar power and battery.

The chicken coop only needs to open and close once a day.

How would I power the Arduino and the stepper motor on a single battery/solar panel? Arduino needs 3.3V-5V and the motor requires 2.8V

I am a complete noob, so bare with me

Do you have a specific question?

Sorry, I edited the original post for more clarification

dolanmiu: Sorry, I edited the original post for more clarification

Thanks. What sort (and size) of battery and solar panel do you have in mind?

And the specs for that stepper motor say 12V, not 2.8V.

A stepper motor is very unlikely to be suitable for that application for a few reasons.

  • First, stepper motors are very inefficient and you will have limited electricity available.
  • Second, a stepper motor needs full power to stay in position even when it is not moving.
  • Third, the Arduino cannot tell what position a stepper motor starts at so there is need a for an external HOME or ZERO switch and code that moves the motor until it triggers that switch to tell the Arduino that the motor is at the home position.
  • Fourth, stepper motors work best with high voltages and specialized stepper drivers

I suggest you use a DC motor with a worm gear. It will hold position without any power. You will need limit switches to detect when the door is fully open or fully closed - but you would need at least one of them with the stepper motor anyway.

...R Stepper Motor Basics

Here is the solar panel I was thinking of: https://www.adafruit.com/products/1781 - battery https://www.adafruit.com/products/390 - charger https://www.adafruit.com/products/200 - solar panel

But I think it may be too weak for what I am trying to do. Any other recommendations?

Second, a stepper motor needs full power to stay in position even when it is not moving.

I forgot to mention that the door is a sliding door, so it does not matter if it retains the position or not

Fourth, stepper motors work best with high voltages and specialized stepper drivers

I have bought an EasyDriver for this purpose

I suggest you use a DC motor with a worm gear.

Sorry, I don't think I could use this because I have already bought a stepper motor and the driver for it :(. And I don't want to re-buy.

I was thinking maybe just using 2 batteries. One for the Arduino and a lead acid battery for the motor... It might be the only viable solution if the motor will constantly need power :sob:

dolanmiu: the only viable solution if the motor will constantly need power

If the door will stay in position without power then you can de-power the stepper motor.

But you will need limit switches at both ends to deal with the situation where the door is moved and the Arduino is not aware of that.

You could power the Arduino from a 12v lead acid battery.

You need to calculate how much energy the Arduino plus the motor will require to figure out how big the solar panel needs to be. The quoted output is usually the maximum, not the average. You must also allow for battery inefficiency. For example, how many consecutive days of cloudy skies can you expect in winter. This JRC website has useful data on solar energy.

...R

If you stick with a 3.7 V cell, you will need a 12 volt, 12 watt boost converter for that stepper motor. The converter won't be very efficient with such a low input voltage. To provide 12 V at 1 amp will require about 4 amperes at 3.7 V, so it won't last long at all.

It is typical, and fascinating, that people who have little or no experience with projects like this, almost always choose and/or buy the batteries and the motors first! Those should be the last purchases, after the requirements are fully understood.

jremington: almost always choose and/or buy the batteries and the motors first

Bicycle shed syndrome

...R

Hmmm... Thanks, the "bike shed syndrome" certainly helps to explain! I learn something new and useful every day.

But you will need limit switches at both ends to deal with the situation where the door is moved and the Arduino is not aware of that.

Could I use a relay for that?

This youtube video does similar to what I want:

https://www.youtube.com/watch?v=tuOrH9sSykk

If I use a relay (so the motor is only used twice a day for opening and closing the gate), how long would the battery last before I have to recharge?

If it is a very long time, then I could just solar power the arduino and have a seperate 12V lead acid battery for the motor

dolanmiu:

But you will need limit switches at both ends to deal with the situation where the door is moved and the Arduino is not aware of that.

Could I use a relay for that?

No. A relay is an output device that is controlled by the Arduino. Limit switches are input devices that provide data for the Arduino.

If I use a relay (so the motor is only used twice a day for opening and closing the gate), how long would the battery last before I have to recharge?

If it is a very long time, then I could just solar power the arduino and have a seperate 12V lead acid battery for the motor

I have no idea how long a battery would last. A lot depends on the size of the battery. You would need to measure the actual current drawn by the motor.

Very crudely, if the motor draws 1 amp for 20 seconds it will consume 0.33 amp-minutes or 0.0055 amp-hours. If you had a 100 amp-hr battery (which would really be a 50aH battery) that may operate the door 9000 times. But that is unrealistic because the battery would self-discharge over that time. (Please double check my maths).

Also a lead-acid battery should be fully re-charged about once every 7 days.

...R