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Solar power 12 volt car windscreen washer pump (Time Adjustable)

Discussion in 'Power Electronics' started by Theovt, Sep 26, 2018.

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  1. Theovt


    Sep 26, 2018
    Problem Statement:
    We are developing a product to purify water. As part of our design, it is necessary to pump very small
    amounts of salty/polluted water to a height of approximately 2m above ground level.
    We have found a suitable pump that works nicely for our application. However, we have no expertise with
    electronics and there is a need to control the pump in a way to make it switch on and off in very specific
    increments of time under direct solar power.

    The Water Pump:
    The kind of pump that we would like to use is a 12 volt car windscreen washer water pump. It is a generic
    type pump that one can purchase at any car parts store such as Midas (We believe it is for a VW Golf).
    Unfortunately, there are no specifications available for this kind of pump (Specs such as Watts/Amps etc).

    The power supply:
    We would like to power this pump with a solar panel. We require advice regarding the minimum size of
    solar panel that would be required. We currently have a 20-Watt Solar panel and when we wire this directly
    to the pump, it works nicely. However, we believe this size panel might be more powerful than is

    Its is not necessary to incorporate a battery in our power supply system. If there is no sunshine, then the
    water production system does not operate. However, with that being said, if you believe it would not be
    complicated or expensive to incorporate a battery into the design, then we would appreciate your advice in
    that regard as a separate option. This would be useful information for another application that we have in

    The electronics:
    The pump is not allowed to run continuously because these motors tend to burn out easily under
    continuous operation. Some kind of adjustable electronic switching device is required to control the pump.
    The aim is to be able to set the pump to come on every minute for approximately 5-10 seconds and then
    switch off again and repeat the cycle for every other minute throughout the day. It would be great if the
    switching mechanism gives us maximum freedom and precision with small increments of time.
    Furthermore, if there are any other special electronic components that would be required, such as voltage
    regulators etc, then we would really appreciate advice on those aspects.

    The pump and electronics will be installed outside / exposed to elements, so if there are any
    recommendations for housing the electronics / enclosures etc, we would also appreciate that advice.
    Ideally, we would need assistance with all electronic aspects to make this vision a reality. We have no
    experience with electronics or how to wire things up correctly or even what kind of wire and connections to

    See attached for more details.

    Attached Files:

  2. Bluejets


    Oct 5, 2014
    I doubt that particular pump will give much service life even considering it is of VW origin.
    That plus the type of impurities would give the motor a real hard time considering they are made for fresh clean water.
    Simple fact is, although in their designed environment they may last for 10 years or more, your application puts much greater demand on it's ability.
    Motor current can be derived from simply measuring with a standard multimeter with a 10 or 20A range.
    12v 20w panel is around 1.5A so maybe a bit on the lean side. You will have to test and see.
    Will not matter as far as the motor is concerned as it will run maybe a bit slower, i.e. if it lifts the required amount of water and does so in the required time, that's the definition of power. If that will suffice, then fine, no drama.

    What will be of concern is any controls that will need a suitable stable supply to operate properly.
    Battery could be incorporated just for this, not the motor, in the form of sealed lead acid to be economical and long lasting. Battery could be recharged from same or separate solar panel as long as the panel is of sufficient size.

    As a final note, I doubt you will get anyone here to do a complete system design for you.
    Assistance yes but complete designs cost.
    Last edited: Sep 27, 2018
  3. Theovt


    Sep 26, 2018
    Thanks for the feedback. Much appreciated.

    Have you got any suggestions for another kind of pump that would be more suitable to the proposed application?

    Could you perhaps share your thoughts on the timing device to make the pump switch on and off at precise time intervals?
  4. kellys_eye


    Jun 25, 2010
    A 'minutes' counter operating a 5-10 second monostable and switching a PWM driver would fit the bill. Mounted inside an IP65 (or better i.e. IP66, IP67, IP68) housing for environmental purposes.

    A design with a small solar panel on the outer lid, feeding an 18650 lithium cell with appropriate buck/boost converters would make a stand-alone, self-contained system that would work for as long as the motor lasted.

    But as for VW - have you tested the carbon monoxide output of the motor? It's probably WAAAAY too high....o_O
  5. Bluejets


    Oct 5, 2014
    Many types of timer modules available at low cost and reasonable quality on Ebay. Depends on what your requirements are as to which one.
    As for the pump, I'd be inclined to go for a magnetic drive as there is no shaft seals to breakdown and parts are usually made from a type of carbon plastic so resistant to most impurities the worst being salt content.
  6. MidNor


    Sep 24, 2018
    Hi theovtt
    I see you are from South Africa, I am from lydenburg and can assist you with the design. I have send my number to you check your messages.
    I amarather thinkingtof pumpipumthe water into a resouvar rather than having a batery. Then just regulate the waterflow from the resouvar.
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