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12v auto pump from 110v?

Discussion in 'Electronic Design' started by T-n-T, Dec 7, 2006.

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  1. T-n-T

    T-n-T Guest

    Can a 12v windshield wiper pump be run from a wall wart? I am putting
    together a mist system for a terrarium, so it will run about 1 minute
    2-3 times a day or so. If it will run from a wall wart any suggestions
    would be great.

  2. Guest

    I bought one for home experiments a few years ago, and from experience,
    they get pretty warm within a few seconds, and they're not meant for
    continuous use. I also think they don't like to be run dry, but
    running dry for a second or so shouldn't hurt it too badly.

    Make sure your wall-wart can provide the necessary current.

    Other than that, knock yourself out. ;-)

  3. If the wall wart has a rectified (DC) output and a
    reasonably close to 12 volt output and enough current
    capacity to run the motor, then it should work just fine.
  4. T-n-T

    T-n-T Guest

    Anyone know the aperage of a automobile system?
  5. Guest

    Guessing about an amp or so.

    You can always run an experiment to find out... get a digital
    multimeter, set it to measure current, and connect it in SERIES with
    the windshield wiper motor, connected temporarily to your car battery
    (small alligator clips work great).

    Make sure the pump is sucking water, even if it's just cycling through
    a bucket, to get a reading for while the pump is under load (and so you
    won't run it try, ruining it). And don't get it wet, and don't let any
    wires touch the car metal ground...

    Guys, did I leave anything out..?

  6. Jim Thompson

    Jim Thompson Guest

    Radio Shack makes an A/C adapter with a "cigarette lighter" receptacle
    that can supply several amps. I used one once to test an automotive
    product without having to have a lead-acid battery in the lab.

    ...Jim Thompson
  7. Don Bowey

    Don Bowey Guest

    Wrong question, You want to know how much current the pump motor draws at
    12V, I suspect the current needed will be printed or etched on the pump
    motor. I also guess it could be several Amps.

  8. Guest

    And don't forget the startup surge current, which can be several
    factors above steady-state current draw.

    I don't recall my pump motor specifying the current draw...

    FWIW, I ran mine from 4 D cells (6V), which was just fine with the low
    flowrates I was using.

  9. neon


    Oct 21, 2006
    lets reinvent the wheel how about a cheap timer 120v ac cycle water as mist. the pump is allready working for you as some remote pumping station giving you ~90 psi all you need is a switch to turn it on like a solenoid or garden 24v controller. not design requiered just inplementation. And wall mart sell of these items including the mist fitting.
  10. Rich Grise

    Rich Grise Guest

    If all you need is a mist for a terrarium, then a windshield washer motor
    is probably overkill - you don't need anywheres near that much of a flow
    rate. I'd check aquarium filter pumps, and that sort of thing. The fun
    part of the project is going to be finding nozzles, and getting them
    hooked up. :)

    Or, you could go totally goofy, and get hand sprayers and arrange a little
    motor and cam to press the trigger a few times. ;-)

    Good Luck!
  11. PeterD

    PeterD Guest

    The washer pump? Yes, several amps. More current than you'd realize,
    they are terribly inefficient. And noisy.

    There are several fuel pump designs that will work with water! (not
    the rotary ones, but there are designs that use a plunger with a
    solenoid driver). They may do a better job doing what you want. (Big
    may, not sure if they'd last an incredibly long time).
  12. Joel Kolstad

    Joel Kolstad Guest

    What happens if you try to use water with the rotary ones?

    I once replaced a fuel pump on a Crown Victoria, sold the car and had the pump
    die again the day before I was supposed to deliver the car to the buyer.
    @#[email protected]#%*( The deal fell through of course, and I got to replace the pump
    *again*. The second time around there was so little time left the car was
    sold to a dealer for next to nothing. @#@#$%!
  13. Ken Moffett

    Ken Moffett Guest


    Forget the windshild washer pumps!

    I tried using them (several different ones) for an automatic Christmas tree
    watering system. They only had to pump for a minute or so a couple of times
    a day to refill the stand's bowl. Every one melted the bearings. The
    bearings are plastic. Think about how they are designed to be used. A
    couple of brief one second runs to get a little juice on the windshield.
    They can't stand the heat generated by running them for "long" periods. I
    finally went to the miniature decorative fountain pumps, but these would
    not have enough pressure for your purpose.

  14. Guest

    Wow, aren't fuel pumps kind of expensive? Kragen lists them starting
    at $100+.

    These pumps are looking better and better...

    I'm going to need a pump that can pump a conductive fluid (dissolved
    baking soda), and I'd *really* prefer *not* to have to use a
    submersible aquarium pump. 110VAC... submersible pump... conductive
    fluid... not a safe mix.

  15. Jim Thompson

    Jim Thompson Guest

    Is it "tap" water (pressurized)? If so just use a mist nozzle from an
    outdoor "bubbler" irrigation system, and a solenoid valve body
    (nominally 28V, but AC, so all you need is a transformer).

    ...Jim Thompson
  16. John G

    John G Guest

    I have a 12 volt submersible pump in an outside pond that has been
    operating at the bottom of the pond for several years with no problem.

    The HF pumps look far too big for the job but you have not told us ho
    big your Terrarium is.
  17. jasen

    jasen Guest

    Just the little squirter pump motor?

    I measured 2A continuous (more than I expected, but all auto electrics seems
    suprisingly inefficient) that'd be a large wall-wart or a small brick. or it
    could just be my cheap DMM playing up.

  18. jasen

    jasen Guest

    I've seen central-locking actuators used for that.
  19. PeterD

    PeterD Guest

    If it is all stainless, it might be OK. Some are, but they are
    expensive. A non-stainless (cheap ones) would rust quickly.

    The plunger/solenoid ones are mostly plastic.
  20. PeterD

    PeterD Guest

    I get the plunger/solenoid pumps for about $35 to $40 at the parts
    store (I do get a discount, but not that much). The rotary ones are
    expensive, even the cheap ones are more than $100! <bg>

    Regardless these are not an optimal solution, IMHO. Nothing beats
    using the right pump for the job.

    Now, thinking about it, maybe Northern Tools (used to be Northern
    Hydraulic) has lots of pumps, and probably has just what the OP wants.
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