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Topic: Power a 12V water pump by a 12V battery through a relay (Read 2985 times) previous topic - next topic

wvmarle

#15
Jun 05, 2019, 05:13 am Last Edit: Jun 05, 2019, 05:14 am by wvmarle
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.


AntroxEv

You didn't like the answers you got already?
Apologies,
I did not hide the link in my post, I though to continue in the Project section because now the topic is more general than the initial title
but is is ok


Didn't look at things really closely, but you need to connect all the grounds. Do you have any specific problems or questions?
I will try the wiring according that schematic soon (if it is correct).
Is it missing the connection ground arduino with ground relay?
What is the purpose of having common ground?




Let's see the actual wiring.

That relay board has 5V relays, not 12V.

Make sure the relay jumper is removed.

Add a reversed biased kickback diode across the motor.


Sorry I cannot visualize your imagine.
Regarding the diode, by using a relay I decoupled pump and arduino, Do I need a diode?

Cheers

larryd


Let's see the actual wiring.
That relay board has 5V relays, not 12V.
Make sure the relay jumper is removed.
Add a reversed biased kickback diode across the motor.


You need the diode to snub out inductive switching spikes.



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AntroxEv

Hi all,
I am catching up with the project. Before using a 12V battery and pump, I tried to devise a system for a 9V battery and 9V motor (modifying one Arduino starter project).

I attached two photos of the configuration I tried.

Clicking on the switch button, Arduino send a LOW signal to the Relay and the motor starts spinning.

I connect the positive of the 9V battery to the COM of the relay, I used a wire to connect the NO of the relay to the positive wire of the motor. Both negative of the motor and battery are connect to a common ground to Arduino GND.

I used a diode 1N407 between positive and negative of the motor.

Everything seems working; clicking the button, the IN1 led switches on, a tick is heard and the motor starts.

My questions are:

1) I did not remove the jumper VCC-JDVCC. Is the diode I added in the schematic enough to protect Arduino from the back EMF?
2) If I remove the jumper, do I need a third external power supply or can I use the 9V battery to power the relay and the motor?
3) Compare to other relay I did not find a GND from JD-VCC. Is that a problem?
4) Does JD-VCC supplies power to the coil or also to the motor? I mean, by leaving the jumper the motor is powered just from the 9V battery or the JD-VCC contributes to raise the voltage/intensity?

Thanks for any reply. When I am sure to do not damage anything, I will change the 9V battery with the 12V and the motor with the water pump.
Thanks

wvmarle

As long as the motor and the Arduino are on completely separate circuits (which the relay can ensure - for some reason it seems you did connect the Arduino ground with the motor ground thus completely undoing this isolation) there will be no problem at all.

The JD-Vcc is for powering the relay coil. The relay coil is electrically isolated from the relay contacts. The relay coil needs its own flyback diode (probably on the PCB of your relay module already).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

larryd








Your relay board coils are 5v , they are not 12v.






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AntroxEv








Your relay board coils are 5v , they are not 12v.








Thank you larryd for your reply and pics.
I was actually writing a response quoting you but you anticipated me.

I supply the coils by Arduino 5V output. The relay is not supplied by the 12V battery (only the motor)

In the picture you posted, you are showing a separated 5V supply for the relay. Hence, it seems a need three power suppliers, one for arduino, one for the motor and one for the relay?

 

AntroxEv

 
As long as the motor and the Arduino are on completely separate circuits (which the relay can ensure - for some reason it seems you did connect the Arduino ground with the motor ground thus completely undoing this isolation) there will be no problem at all.

The JD-Vcc is for powering the relay coil. The relay coil is electrically isolated from the relay contacts. The relay coil needs its own flyback diode (probably on the PCB of your relay module already).
Now I moved to the almost final configuration with a 12v battery (the GP23 just for test, it will be replaced by a scooter battery) and the water pump. I created two separated circuits as you said.
I removed the diode, hence, I am not sure it is correct since I do not know if the back EMF can damage the battery. I understand I have to follow larryd's guidance for it.

So far, my schematic is working but I am not sure if it safe.

attached a photo


larryd



The coils on the relay board will need an external 5v power supply as shown in the image in post #21.

Do not use the Arduino 5v power for these coils, i.e. remove the jumper on the relay board and follow the drawing offered to you.

This image expands what is happening in the (8 channel) relay board.
In your case the GND screw on the relay board will go to your external 5v power supply.



EDIT

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larryd

You have the option of using the external 5v supply to power the Arduino if the Arduino is disconnected from the USB jack. In this case you would leave the jumper installed.

However, this is a significant tradeoff where you have now defeated the isolation offered by the Otpo coupler.





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AntroxEv

You have the option of using the external 5v supply to power the Arduino if the Arduino is disconnected from the USB jack. In this case you would leave the jumper installed.

However, this is a significant tradeoff where you have now defeated the isolation offered by the Otpo coupler.



The final configuration (see earlier posts) requires to use the 12V battery to supply Arduino and the motor.
I have to calculate if I have enough capacity to power Arduino for 15 days.


larryd

Quote
I have to calculate if I have enough capacity to power Arduino for 15 days.
A test run will prove your calculations :) .


BTW/FYI






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larryd

Quote
The final configuration (see earlier posts) requires to use the 12V battery to supply Arduino and the motor.
If you do this, there will be no isolation from the Arduino to the motor.

You might as well get rid of the relay board and just drive the motor with an N-MOSFET.

You 'may experience' noise at the load disrupting the Arduino.






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larryd

Show us what 'you' expect will be the final schematic for this project.

Make sure you show all your connections.










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