TWO 12 VDC BATTERIES CONTROLLED BY ONE DPST SWITCH

Discussion in 'The Projects Forum' started by FALCON56, May 3, 2015.

  1. FALCON56

    Thread Starter New Member

    May 3, 2015
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    4. TWO BATTERIES, ONE SWITCH.jpg 4. TWO BATTERIES, ONE SWITCH.jpg 4. TWO BATTERIES, ONE SWITCH.jpg I have a separate Alarm System and a separate Strobe Light System; both are activated by Motion sensors. Each System is powered by a 12 VDC battery (total of two batteries) and the batteries are located about 50 feet from one another.

    I would like to control both systems (on/off) with one DPST top-hat switch and have attached a wiring diagram that I think will do the job. PLEASE NOTE: all wires to and from the switch are from the negative side of both batteries. My question is: Will this work and not affect the voltage leading to either System.


    I should probably mention here that I know just enough about electricity to cause myself bodily harm, but I think this will work.
     
  2. Søren

    Senior Member

    Sep 2, 2006
    472
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    A DPST switch is like two separate SPST switches "glued" together, so it will work.
    Use a good quality switch though, to avoid the risk of "cross contamination" in case of physical failure - a more fail-proof idea would be to couple two physically separate SPST switches, so that you switch both with a single lever or button.

    The only thing you accomplish by breaking the negative side rather than the positive, is to avoid common conventions and frankly, that's a very silly way to be a rebel :D
    IOW, connect the negative line of both circuits and switch the positive lines instead.

    If you use Double Throw switches, with the batteries positive lines on the common terminals, you could charge (if apliccable) in the "off" position.
     
  3. WBahn

    Moderator

    Mar 31, 2012
    17,725
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    I don't follow your diagram. You say you have a DPST switch, which would mean that you have four terminals on it. You are only showing two. I think I can guess what you mean, but drawing circuit diagrams that require people to guess what they mean isn't a very good idea.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    I already reedit the font size.
    Please don't use the big font next time, it looks like something wrong.
     
  5. FALCON56

    Thread Starter New Member

    May 3, 2015
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    OOPS, sorry about that; didn't know.
     
  6. FALCON56

    Thread Starter New Member

    May 3, 2015
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    Sorry, I meant that I want to use a Single Pole, Single Throw; that's what is on the diagram. I like your recommendation of the DPST switch instead and will run the positive lines through it rather than the negative.
    With a name like Robert E. Lee, I can't be anything else but a rebel. :confused:
    Thank you for your help.
     
  7. FALCON56

    Thread Starter New Member

    May 3, 2015
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    Sorry, that IS a SPST on the diagram. I'm going to take Saren's advice and use a DPST. I'll also run the positive wires through the switch instead of the negatives. Like I said in my original post, I know just enough about electricity to cause myself some bodily harm. Thank you for your help. :)
     
  8. FALCON56

    Thread Starter New Member

    May 3, 2015
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    Problem solved! Today I purchased a DPST toggle switch. I also learned a few things on the forum replies, so thank you to all.
     
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
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    You did ensure the switch is rated for the current and voltage from your batteries right?
     
  10. FALCON56

    Thread Starter New Member

    May 3, 2015
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    As a matter of fact I did remember to check that. I surprised myself!
     
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