DC Motor Controller

[Rock Doctor]

Greetings. I am out of my depth trying to adjust my solar water pump to a lower rate. Not sure I need a brushless controller or a brush controller…and more importantly the specs of a controller that I need. HELP!!
My motor is as follows.
24V brushless motor submersible water pump
1/3 hp
Internal controller
Typical operating current is 10-11.00A.
The stall current is around 12.00A.
The pump can start around 150W. Max power is 250W
Only has two wires to the pump. Positive and Negative.
I need to dial the rate down almost 75% to the appropriate pump rate.

 

[ahsrabrifat]

Since the motor already has an internal controller, you don’t need a brushless motor controller. You only need a high-current adjustable DC voltage source like a buck converter.

 

[D.A.(Tony)Stewart]

What does the manual say?

? RPM depends on input voltage and load?

Do you have a link? for pump and Solar panel specs?

 

[wwfeldman]

why do you need to reduce the pump rate?

 

[dpr3]

It's interesting to see the different approaches to DC motor control being discussed. For the original poster's question about a simple controller, I'd suggest looking into using a PWM-based solution with a MOSFET. This allows for smooth speed control by varying the duty cycle. If precise speed regulation is needed, adding a feedback loop with an encoder or back-EMF sensing would be beneficial, as mentioned by others in the thread. The specific components and complexity depend heavily on the motor's power requirements and the desired control accuracy.

 

[KlausST]

I´m with Tony.
We need clear informations first.

I wonder why the OP shouts he needs "HELP!" ... but then is not interested in any communication at all.

Klaus

 

[BradtheRad]

I lived in a house with well water. A new submersible pump blew fuses until a plumber narrowed the inline valve slowing water flow. I believe the well filled at a slow rate so it quickly ran dry. It was only 30 feet below cellar floor and I think only replenished at a gallon or two per minute. That's a reason for slowing pump speed.

Check how your ballast (storage) tank is performing. It's supposed to be partly filled with air under pressure, probably 20 to 50 lbs. This is also the pressure inside your system of pipes. Water is admitted to the tank under pump pressure. Somewhere a sensor reacts to the pressure ups and downs. It starts the pump and shuts it off. Making changes affects how your equipment interacts. You may only need to partially shade the solar panels in order to reduce supply voltage.

 

[dpr3]

I lived in a house with well water. A new submersible pump blew fuses until a plumber narrowed the inline valve slowing water flow. I believe the well filled at a slow rate so it quickly ran dry. It was only 30 feet below cellar floor and I think only replenished at a gallon or two per minute. That's a reason for slowing pump speed.

Check how your ballast (storage) tank is performing. It's supposed to be partly filled with air under pressure, probably 20 to 50 lbs. This is also the pressure inside your system of pipes. Water is admitted to the tank under pump pressure. Somewhere a sensor reacts to the pressure ups and downs. It starts the pump and shuts it off. Making changes affects how your equipment interacts. You may only need to partially shade the solar panels in order to reduce supply voltage.

The experience with your well water system highlights the importance of matching pump capacity to well yield. A slow-recharging well, like yours estimated at a gallon or two per minute, can easily run dry if the pump extracts water too quickly. The plumber's solution of throttling the inline valve effectively reduced the pump's flow rate, preventing it from emptying the well too fast and thus stopping the fuse blowing. As suggested, checking the ballast tank's air pressure is crucial for proper system operation, as it regulates pressure and controls the pump's on/off cycles.

 

[KlausST]

Hi,

to prevent pum from run dry I´d install a water level switch.
Like many dirt water pumps already have installed.

Klaus

 

[Rock Doctor]

What does the manual say?

? RPM depends on input voltage and load?

Do you have a link? for pump and Solar panel specs?

The manual shows nothing. https://cdn.shopify.com/s/files/1/0494/2577/6801/files/Solar_Water_Pump_Manual.pdf?v=1692215811

 

[Rock Doctor]

why do you need to reduce the pump rate?

My spring on produces 2.5 gallons per minute. The pump as installed will pump more than 7.5 gallons per minute. So I need to slow down the pump to equalize the flows.

 

[Rock Doctor]

Hi,

to prevent pum from run dry I´d install a water level switch.
Like many dirt water pumps already have installed.

Klaus

I agree that is an option. I thought the DC controller would be an easier fix to reduce the rate. The other fix is as you note put in a switch to turn the pump on and off. https://www.amazon.ca/gp/product/B0D4HLXRH2/ref=ox_sc_saved_image_2?smid=AXCLEYFPOC3GC&psc=1

I´m with Tony.
We need clear informations first.

I wonder why the OP shouts he needs "HELP!" ... but then is not interested in any communication at all.

Klaus

Apologies.

Since the motor already has an internal controller, you don’t need a brushless motor controller. You only need a high-current adjustable DC voltage source like a buck converter.

Not sure what a buck converter is? I was thinking that since the brushless pump has the internal controller I could use an external controller sized to the pump and it would allow me to reduce the power to the pump…and hence reduce pump rate…https://www.amazon.ca/gp/product/B0BVGKZHLS/ref=ox_sc_saved_title_9?smid=AWHPP0851IO04&psc=1

 

[D.A.(Tony)Stewart]

Have you tried contacting the OEM?
I asked Grok AI and put the result in a text file.
I don't have time TL;DR perhaps others can help.
good luck
Tony

 

[Rock Doctor]

I lived in a house with well water. A new submersible pump blew fuses until a plumber narrowed the inline valve slowing water flow. I believe the well filled at a slow rate so it quickly ran dry. It was only 30 feet below cellar floor and I think only replenished at a gallon or two per minute. That's a reason for slowing pump speed.

Check how your ballast (storage) tank is performing. It's supposed to be partly filled with air under pressure, probably 20 to 50 lbs. This is also the pressure inside your system of pipes. Water is admitted to the tank under pump pressure. Somewhere a sensor reacts to the pressure ups and downs. It starts the pump and shuts it off. Making changes affects how your equipment interacts. You may only need to partially shade the solar panels in order to reduce supply voltage.

Thanks for that. It is not a well but a spring filling water totes which I then pump “up” the mountain to other totes to gravity feed our house.

Have you tried contacting the OEM?
I asked Grok AI and put the result in a text file.
I don't have time TL;DR perhaps others can help.
good luck
Tony

Thanks.

 

[kd502]

Not sure what a buck converter is? I was thinking that since the brushless pump has the internal controller I could use an external controller sized to the pump and it would allow me to reduce the power to the pump…and hence reduce pump rate

Buck converter converts higher DC voltage to lower DC voltage. You can connect PWM (chopped DC) to brushed motor, but you cannot connect PWM at the at the power input of the brushless motor controller. Something will burn if you do.

Electronic devices don't accept PWM where manual requires DC. PWM is not DC.
PWM is possible only if your controller have special input for PWM. If there is no such input use supply with lower DC voltage. Some circuits have under voltage lockout.

 

[Rock Doctor]

Buck converter converts higher DC voltage to lower DC voltage. You can connect PWM (chopped DC) to brushed motor, but you cannot connect PWM at the at the power input of the brushless motor controller. Something will burn if you do.

Electronic devices don't accept PWM where manual requires DC. PWM is not DC.
PWM is possible only if your controller have special input for PWM. If there is no such input use supply with lower DC voltage. Some circuits have under voltage lockout.

But if my solar battery is 24v and my pump is 24v. Won’t the Buck Converter “decrease” the voltage (<24v) in hopes of decreasing the pump rate BUT damage the 24v system?

 

[BradtheRad]

The instructions (link found in post #10) tell the supply ('DC input') voltage can be 11-55V.
It's hard to be certain if you must apply a certain voltage to start the pump spinning. Then you can reduce voltage in order to reduce its rpm.
The final page has specs saying its a DC brush motor.