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trying to build a charging system

Discussion in 'Robotics & Mechatronics' started by bruttis3668, Apr 20, 2012.

  1. bruttis3668

    bruttis3668 New Member

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    my class is building a robot for capstone we have 2 24v dc motors being powered by 2 12vdc drill batteries wired in series to produce the 24 v.
    what i need help with is to build a charging system that uses a 12vdc adapter and when it is plugged in switch the batteries from series to parallel in order for the battery paks to charge.

    any help would be greatly helpful.
     
  2. colin55

    colin55 Well-Known Member

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    This circuit allows to you charge a 24v project from a 12v charger. It converts the two 12v batteries from series to parallel:
    [​IMG]
     
  3. Emilrudin

    Emilrudin New Member

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    Where can i buy that switch and what is the name of it?
     
  4. dave

    Dave New Member

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  5. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Hi Emilrudin,

    It's a standard DPDT (double-pole, double-throw) switch. Telling you where to buy it is difficult because you didn't put your location in your profile, but I would start with Digikey or Mouser.

    It's a very standard type of switch, there are millions of options out there that would work.
     
  6. audioguru

    audioguru Well-Known Member Most Helpful Member

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    A 12V battery needs a higher charging voltage of about 14V. From a 12V adapter?? No.
    To charge a battery you must limit the current. Where is your current-limiting resistor?
     
  7. Emilrudin

    Emilrudin New Member

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    Hi! I come from Sweden.
    Sorry for bad english!

    But I got 2 wheelchair motors 17.5 amp eatch. So i think i need a switch that coud hadle about 40 a?
     
  8. Dave Mason

    Dave Mason New Member

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    Did anyone ever get a schematic?
    Is the top right terminal shorted to the middle left terminal?
     
  9. flatfootskier

    flatfootskier Member

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    double post
     
    Last edited: Jul 31, 2017
  10. flatfootskier

    flatfootskier Member

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    erroneous attachment removed
    Expanding on the above, I *think* this is right, and should avoid any conflict between the 2. Not checked it though
     

    Attached Files:

    Last edited: Jul 31, 2017
  11. flatfootskier

    flatfootskier Member

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    forget that - it's got a mistake, sorry. will correct later
     
  12. flatfootskier

    flatfootskier Member

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    Third time lucky
    upload_2017-7-31_15-59-25.png

    If you forget to flick the switch though you could end up charging just one battery, not both
     
    Last edited: Jul 31, 2017
  13. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    You can use two chargers and no switch.
     
  14. N11778

    N11778 New Member

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    this is more like what you explained you wanted
    Car or truck trailer connectors if you need more amps
    no switch RobotCharger.jpeg
     
  15. Dave Mason

    Dave Mason New Member

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    ....
    Good solution! Would be better if both 12VDC leads (sets) were separaded/isolated into two separate 12VDC - since I think the original poster wanted to charge the Two 12V batteries separately.
    Just my 2.5 cents/worth....
     
  16. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Question about two batteries in parallel:
    If you have two batteries running in series (24V) and they discharge slightly differently they might not have the same voltage when the "switch" is flipped and they are now in parallel. I am thinking about the spark when a 12V battery is connected across a 11V battery.
    Is this a problem?
     

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