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How do I reduce the speed of a 12v childrens car

Discussion in 'General Electronics Discussion' started by surreyman, Sep 18, 2018.

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  1. surreyman

    surreyman

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    Sep 18, 2018
    Hi all , i would be so grateful for any help- i have bought a half scale electric willys jeep for my 5 year old son. It currently runs on three car batteries wired in series which are connected via a progressive accelator unit to an 1100 Wat motor. The problem is that it does over 20mph and he could badly hurt himself as the car is heavy. I would like some advise as to how to put in some speed regulator. preferably something that i can turn up/down depending on who is using it. Will happily post pics if someone tells me how on this site! Any help appreciated
     
  2. BobK

    BobK

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    Jan 5, 2010
    In order of increasing difficulty:

    1. Run it from two or one batteries. Simply move the + cable to do that.

    2. Mechanically limit the accelerator.

    3. Modify the electronic controller. We would need a lot more info for that. A start would be a picture of it.

    Bob
     
  3. Minder

    Minder

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    Apr 24, 2015
    Presumably a DC brushed motor,
    Depending on the type of controller you have, you could first try reducing the supply by removing a battery (or maybe two).
    More on the type of controller would help, but it should not do any damage by trying the battery reduction first.
    If there is a built in charger, it may want to see 4 batteries at this point though.
    M.
     
  4. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    I'd rewire the 3 batteries from series to parallel connections.
    The battery runtime will increase and speed will go down to probably about 6 mph.
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    I say it will depend on the speed controller whether this will work or not.
    If the speed controller is a simple rheostat type, there should be no problem.
    If it is an electronic speed controller, it will possibly not work with too low a battery voltage.
    We'll need to know more about the controller, as Minder requested.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Yup. Threads merged, thanks for noticing.
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Change the gear ratio? Requires no modification of the electrics/electronics at all.
     
  8. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    I agree that more needs to be known to say for sure.
    A few years ago I modified a hotwheels type car and there was no controller or reostat only switches to control speed. I assumed it was a similar design.
     
  9. BobK

    BobK

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    Jan 5, 2010
    A rheostat for an 1100 Watt motor would be something to see!

    Bob
     
  10. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    @surryman, To upload picture, click upload a file button below, then click browse to locate the location of your picture.
     
  11. surreyman

    surreyman

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    Sep 18, 2018
    hi, i disconnected one battery and the car simply did not run
     
  12. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    We need to know more info about this circuit. Sketch or pictures of components.

    You can't simply disconnect one battery.
     
  13. Minder

    Minder

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    Apr 24, 2015
    Sort of an obvious question, but did you connect the remaining three properly?
    M.
     
  14. surreyman

    surreyman

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    Sep 18, 2018
    Yes I think so !
     

    Attached Files:

  15. surreyman

    surreyman

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    Sep 18, 2018
    I one of the pictures you can see the speed regulator that's attached to the end of the accelerator
     

    Attached Files:

  16. surreyman

    surreyman

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    Sep 18, 2018
    So I disconnected completely /removed the live to neutral on the bottom battery and removed the cable . I then moved the negative on the bottom battery and moved it to the negative on the one above . Thereby the bottom battery had no connection to it at all. The jeep would not run
     
  17. Minder

    Minder

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    Apr 24, 2015
    I just see batteries. I don't see any controller, Is that an accelerator linkage or ?
    Is that it at the top of the picture?
    Not the best solution, but is there any means of limiting the stroke of the rod?
    M.
     
    Last edited: Sep 18, 2018
  18. surreyman

    surreyman

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    Sep 18, 2018
    yes the middle pic is the top accelerator linkage that slides the plastic speed regulator in an out- there are two wires that come from this and dissapear towards the rear. idealy what i need is another adjustable speed regulator after this first one
     
  19. Minder

    Minder

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    Apr 24, 2015
    I don't see why the present one could not be limited somehow, too bad there is not more detail on it.
    M.
     
  20. surreyman

    surreyman

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    Sep 18, 2018
    i will ask the manufactures for its specification
     
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