As I specified in the title I started an irrigation system where I use a deep well pump that fills a tank, when this tank is full I want to start an other pump that will push the water from the tank to the plants.
The pump I will use has a DC motor of 48v powered from a solar panel string.
I'm thinking about this sensor AJ-SR04M, because i want to start the pump when the level is almost full and stop it when the level is below x level.
My biggest problem is (I think) that I don't know what relay I should use (or what other component) to stop/start the pump.
Welcome to the forum
Your topic was MOVED to its current forum category which is more appropriate than the original as it is not an Introductory Tutorial
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You can do the stop start pump just with relays the only need for the Arduino is to decide the need to water .
If you are switching a DC pump , then you need a relay with a DC rating that will deal with the starting current - say 5x it’s running current ( or more. )
The relay will not be blue coloured on a small PCB ….look at Farnell /RS components , don’t buy cheap from you know where.
Your solar panel will need to charge a battery that then supplied your pumps .
Look at the economics too , powered off the mains maybe more cost effective
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can you send me please an example of relay to be sure I will search what you recommended!
This solar system has only a controller without a battery, I don't need extra cost or power, it has to work as log as the sun will be up.
Thank you!
Do you know the Wattage (Watts) or Current (Amps) requirements of your motor?
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I think it has somewhere about 10 Amps
can this relay work: https://www.amazon.com/SSR-80DD-3-32VDC-Industrial-Automation-Devices/dp/B08NSHMMNS ?
My friend, please check up on the pump motors. A link to the product data would be very good. Else You might end up using a relay that will get damaged, either On all the tme, or
Off.
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As @hammy pointed you need to buy the relay from a reputable electronic component distributor.
Also "I think 10A" is not good enough, you need to know for sure.
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You seem to be saying you want to power the pump directly from the panels, with no battery. That means you'll need panels capable of delivering the current needs of the pump directly. Probably a poor plan, as what will you do when the panels only have partial sunlight? Now you need more panels... Storage will be your saviour here, allowing you to run the pump in differing light conditions, but (obviously) at the cost of increasing complexity and cost. If you're in an area with months of sun without any cloud, perhaps this is a viable plan, though you'll still need to consider sunrise and sundown conditions.
The pump it’s similar to this one 3" DC Screw Well Solar Water Pump 48V 500W Controller Submersible Pond Fountain 604213294234 | eBay
I don’t need it to run at its maximum capacity, I’m ok with the idea that it will stop or run at low speed/power. In my area, Romania, summer is very sunny
The specifications say 17A max, so I would use a relay with at least a 25A rating.
However, the relay must be rated for an inducive load of 25A at 48VDC and I can't seem to find one.
I suggest that you build a desktop setup that simulates your core hardware to help get your software tested without having to run in and out carrying your Arduino.
A switch can indicate water full ,plus other switches for different levels. An LED for the pump and one of the blue relays @hammy warned you about to get some idea about how to wire them up. If you destroy some parts on the process, it will be less painful.
The best time to water plants is in the cool of the morning. If you water in high sun, to get power for your pump, a lot of the water will be wasted. Also why wait for the tank to be full?
Depends on the irrigation system. Mine doesn’t do any damage to the plants.
A solar panel unless grossly oversized will not be able to supply the current to operate the pump - sunny or not , you need a battery and charging system - as implied this can quickly get expensive and a simplier non solar solution may
Work out better .
Don’t buy cheap stuff from Amazon either , but from a proper industrial supplier
I think I will do a little diy with my current setup.
Short story I have a deep well pump of 600w, powered with 2 solar panels of 370w in series and no battery that pulls out water from a depth of 25-30m. I think it pulls out about 10k -12k litters per day.
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At first I thought 10k-12k liters/day sounded a lot from a 25-30m well. However it turn out it needs between 2500kJ - 3000kJ of energy to do it. If the 600W pump was 100% efficient and running at full capacity it should be able to do it in between, very roughly, 1 to 1.5 hours.
Small pumps might be say 50% efficient so that takes the time to 2 - 3 hours. Although the sun will not be running the pump at full capacity all the time the numbers seem to agree with practical experience.
It would be interesting to know the specification of the pump in terms voltage, current, and flowrates. Do you know these or the make and model of the pump?
You have not said why you want to only pump from the tank once it is full, why is that? Are you intending power both pumps from the one pair of solar panels but just have one pump running at a time?
Submersible means your pump must be covered with water in order to operate. It cannot ever be run dry. Does your tank have enough depth?