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Diode across Peltier to prevent reverse function

Discussion in 'General Electronics Discussion' started by fatman57, Nov 5, 2016.

  1. fatman57

    fatman57

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    May 27, 2013
    I am building a cooling application with a Peltier. I expect the Peltier to not be on the full time, but do not want it to generate electricity when it is not on and there is a temperature differential between the two sides.

    Would a diode across the Peltier as illustrated in the image below allow it to function as normal when 12v is applied to the + side and when it is turned off any energy generated by the Peltier will feed back into itself? My hope is this should at least slow down the heat transfer process from the thing it was cooling to the outside world?

    I am also interested/worried about how this reverse in flow direction will affect the circuitry of my system, and wondered if this would help protect against that.

    Thanking you in advance.

    [​IMG]
     
  2. Kiwi

    Kiwi

    312
    70
    Jan 28, 2013
    Would a diode in series be a better option?
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Yes, this calls for a series diode
     
  4. fatman57

    fatman57

    102
    0
    May 27, 2013
    OK thanks, where and in which orientation? I cannot see how a series diode will both prevent the backwards flow of energy but also route it through the Peltier again. Thanks!
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    A diode will only allow current to flow one way.

    Places with the anode toward the +ve side of your power supply, it will allow power to flow from the power supply to the Peltier, but not flow in the reverse direction
     
  6. Chemelec

    Chemelec

    291
    47
    Jul 12, 2016
    Adding the Series Diode Will prevent Back flow into your Drive Circuit, But it will Not improve efficiency.
    And "I seriously doubt it could affect the Circuitry of your System".
    And it is not possible to re-route this power back into the Peltier.
     
  7. fatman57

    fatman57

    102
    0
    May 27, 2013
    Thanks, I had actually stopped answering because I looked at it again and thought how it couldn't work, but i do need to say thanks to people that used their valuable time to reply.

    I think I could get something similar by using pairs of Peltiers and wiring them in series, then use a power supply with double voltage to compensate for normal running and when off one can feed the other - but this is just the first thought into my head haven't looked into it yet. I don't want to sound too stupid!

    And thanks for the comment on the circuitry - I was worried what would happen with the reverse of polarity on my PSU for example, but I presume it can handle this.
     
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