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Inexpensive Automated Solar Pump with Timer

Description:

This is a water pumping system for a well or borehole, which does not require manual on/off switching.
Impetus:

After losing several water pumps in less than one year, I set out for a lasting solution.
The tenants in charge of switching the pumps on/off, would just switch on a pump and let it run until the pump burns out.
So the only solution is to automate the process, and no longer rely on tenants.


Float switch:

First I installed a float switch. This automatically switches off the pump when the water tank is full. It switches it back on when the water level in the tank goes down.
However, sometimes while the pump is working, the well runs out of water. So the pump keeps running without water till it burns out.
That means, the float switch alone is not enough.

Timer:

I did some research, and came up with a Power Socket Timer.
This solution gives me full control over when the pump runs, and at what interval.

By adding a Timer to the setup, you can program it to automatically turn the pump on/off at different times of the day.
For example, the pump can run for 30 minutes, and switch off for one hour. This gives the well/borehole time to recharge.
The above schedule can keep repeating throughout the day. The pump can be programmed for 16 different schedules each day of the week.

With this setup, even if the borehole runs out of water, and the pump spins without water for just 30 minutes, it's not likely to burn out. The timer would switch it off after 30 minutes.


Pump:

That brings me to the question of which pump to choose.
Pumps come in many varieties and prices. I found inexpensive Bilge DC pumps that do high volume pumping.
The only downside to these pumps is that they can only pump to a height of about 10-20ft.
For a 750GPH pump, the maximum recommended vertical lift is 15ft.

Here are videos showing pumping at 7ft elevation by bilge pumps,





So if your well is not too deep, this limited pumping height of 20ft should suffice.
I have seen Bilge pumps sold in pumping capacity from 350GPH to 3,500GPH (i.e. 1,400 liters/hour to 14,000 liters/hour).

Note that the higher you pump the water, the smaller the output.
For example, a pump rated at 500GPH might only output 250GPH if it has to lift the water.

If you have a borehole, or your well is very deep, a Bilge pump won't work for you.
You should go for the more expensive conventional DC/AC pumps. Unfortunately, these cost about 10-20 times more.

I have a page that gives a general overview of different types of pumps.


Wiring schematics for DC pump


The timer and pump above are both DC. If you opt instead for AC pump, you would additionally need an inverter, and the timer must be AC.

Actual Wiring circuit diagram



As you can see in the wiring diagram above, you will need to split some wires into two.
Here is a real life example of how to split a wire (the first two wires from the left are both split)...




Required components:
  1. Bilge pump 1,100GPH 12V 3.0Amp 36W (4,200 liters per hour)
    https://www.jumia.com.ng/catalog/?q=bilge+pump
    ₦ 5,149

    UPDATE: When the pump was installed, the pumping height was about 4m. We tested the pump for flow at 1 ft and 8 ft of head. Like in all centrifugal pumps the flow is highly dependent on the head (discharge pressure). Usually the published number assumes 0 ft head to make the flow more attractive. So at 1 ft head the measured flow was 810 GPH at 4.0A current consumption from a 12V battery. At 8 ft head the measured flow was 585 GPH at 4.1A current consumption. At 9 ft head, 400-500 GPH of flow.

    So the bilge pump did not serve our purpose, because the depth of the well was more than what the bilge pump could handle.
    It would work perfectly, if for example you want to pump water from a shallow river/pond. 
    
Here is the pump we finally settled for, and the other components...
https://images-na.ssl-images-amazon.com/images/I/71t4dyw2FvL._SX425_.jpg

1. 2x 50w
2. 1x 70m pump
3. 2x 12V 18ah
4. 1x float switch 
5. 1x Timer 
6. 1x charge controller. 

Pump specs:
Voltage: 12V/24V
Current: 8.0max
Flow: 6.5L/min (390L/hr)
Maximum Lift: 230 Feet (70 Meters)
Maximum Submersion: 100 Feet (30 Meters)
Rated Power: 100W
Price: US$80.

The above pump works perfectly with the timer for us now.
How long it would last remains to be seen.


    

I also searched on ebay and found this pump:

Small-Diaphragm-Water-pump
Head: 	70m
Suction lift: 2m
Flow(max): 	8L/min
Voltage: 	DC12V
Power(max): 	100W
Motor lifespan: 3-5 years
US $49

    
Note: This is a surface pump, not submersible. 
That means the pump inlet must be within 2m (78 inches) of the water source. 
Otherwise, the pump would not work. But if the inlet is close, then the outlet can pump up to 50m.

These pumps come in different sizes. Here is another example...

Head:   50m
Suction lift: 2m
Flow(max):      5L/min
Voltage:        DC12V
Power(max):     60W
US $27.99
    

Alternative pump:

generic-2000gph-12v-marine-submersible-bilge-water-pump
2,000GPH 12V, 8A, 96W
No damage if run dry. 
Max head: 6m (20ft).
₦15,149


  2. Charge controller
    https://www.jumia.com.ng/catalog/?q=solar+charge+controller
    ₦ 2,700

  3. Timer
    https://www.jumia.com.ng/catalog/?q=programmable+dc+timer
    N2,500

  4. Float switch
    https://www.jumia.com.ng/catalog/?q=float+switch
    ₦ 2,500

  5. Deep cycle Battery from 7Ah to 40Ah (SMF preferred)
Total cost:
5,149 (pump) +
2,700 (controller) +
2,500 (timer) +
2,500 (float switch) +
7,000 (battery)
= N19,849

The final component for the setup is a solar panel for charging the battery.
What size solar panel do you need?
The size of solar panel depends on your battery capacity, and how much sunlight you get in you area.
Our battery above is 12V 18Ah. That means it is a 216Wh battery. Since we can only discharge the battery to 50%, it means we have a 108Wh battery. So choose a solar panel that is sufficient for battery of that size.
A solar panel that is 10W-30W should be enough.
Currently such solar panel will cost about N3,500 to N10,000.


How many watts does a Bilge pump require to run?

- 500GPH 12V 3A = 36W
- 1,100GPH 12V 5A = 60W
- 2,000GPH 12V, 8A, 96W
- 3,500GPH 12V 15A = 180W

How much maintenance does the pump require?

- Dirt and debris would clog the pump over time. So monitor the water output, and clean the pump when necessary.
- Cover the pump inlet with a screen to prevent debris from getting into the pump.



How to program the timer







Issues with Bilge pumps

Airlock trap problem.
www.youtube.com/watch?v=cweD5wJ6nh8
This happens when hose is not straight.
Some pumps have anti-airlock feature. Check the specs of the pump before you buy.

Longevity

Someone who ran the pumps nonstop 24/7 reported having to replace it about every six months.
www.youtube.com/watch?v=l-7RhTZllXk
But since we're not going to run the pump 24/7, it should last for a few years.

For another person, it lasted about 3 months of daily 6-8 hr use.

These bilge pumps have brushed motor, i.e. not for continuous use because the brushes are consumable, and wear out fast.
A brushless pump like the jebao/jecod can easily work non stop for 10+ years.
However, brushless pumps cost significantly more compared to bilge pumps.

Further cost cutting

If you want to reduce the cost of the system, you can eliminate the battery and the controller.
You just wire the solar panel directly to the timer.
However, the battery insures you against cloudy days.

Youtube videos

www.youtube.com/watch?v=gLhMegglOUY
www.youtube.com/watch?v=v6HetubLu2s
www.youtube.com/watch?v=busLdyIzeDk

www.youtube.com/watch?v=0iEzCOmKVlQ


Questions and comments:





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Richard Akindele, May 2019.