Beer cooler, how does it work?

Discussion in 'General Electronics Chat' started by Gdrumm, Jun 7, 2015.

  1. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    It is a Koolatron Thermo electric cooler, P25, for keeping drinks cool in your RV or whatever.
    It has a 12v DC plug in to the cigarette lighter.

    This one does not get cool.

    I dissected it, and found very few components.
    The small square block seen in the photo gets instantly hot, when I plugged it in.

    Does anyone know how it is supposed to work?

    Thanks,
    Gary
     
  2. LDC3

    Active Member

    Apr 27, 2013
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    It uses a Peltier device to transfer heat from the inside to the outside. Since the plate got hot when you turned it on, it is working properly. Unfortunately, it takes a long time to cool items down, so it is recommended to have the items pre-chilled before you place them in the cooler. The cooler will be able to keep them cold as long as it is on.
     
  3. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    Okay,
    Thanks,
    I will reassemble it with fresh thermal compound, since the old paste looked well used.

    Gary
     
  4. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,147
    204
    Remember to use a thin film. You just want to fill the voids.

    The component is known as a TEC or Thermoelectric Cooler. It's basically a solid state heat pump. Generally, then can with stand a max delta T of 60 C.
    Reversing the leads, reverses the direction of heat flow, so one side is hot and the other cool. They are very inefficient and have an extreme lag in response.
    Exceeding delta T usually ends up with a melted device. They can be placed mechanically in series to increase delta t.

    Fancy controllers use PWM and an H-bridge.to vary the temperature

    A Vortex cooler might be better.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,060
    No fan or control board - it just plugs in? As noted there's a chance it is already working, you just need to give it longer to cool down the heat sink.

    If you have a 5V supply like an old computer PSU, you can power that white slab (the TEC) from it briefly, a second or two. One side will get hot (too hot to touch if you're slow) and the other side will get cool. You can do this test with 12V but don't let it go too long.
     
  6. Brownout

    Well-Known Member

    Jan 10, 2012
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    Ditto. Mine seems to take a day to cool if I place warm items in it.
     
  7. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    It does have a fan (see photo 183).
    Great responses, and thanks Brownout for the timeline to cool warm items.
    I don't drink Beer anymore, but some nice cool lemonaide might be nice, as I drive across Texas.

    You guys are awesome.
    Thanks,
    Gary
     
  8. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    I found an excellent link describing the preferred method of re-assembly.
    http://www.cui.com/product/resource/peltier-application-notes.pdf

    Assuming I can do that, my next question has to do with battery drain.

    If I left this cooler hooked up to my cigarette lighter all day long, while the vehicle is not running, would it drain my battery?
    If so, then the unit would best be used only while the motor is running, etc.

    Thanks,
    Gary
     
  9. wayneh

    Expert

    Sep 9, 2010
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    Yes! It draws several amps at least. You could leave it on longer than you might leave your headlights on, an hour?, but it'll kill the battery faster than a dome light.
     
  10. LDC3

    Active Member

    Apr 27, 2013
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    It says it uses about 4 amps. I'm not certain what the capacity of a car battery is, but it should be good for several hours.
     
  11. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Car batteries aren't made to be deeply discharged. They won't last long. If you're gonna leave it hooked for hours, use a deep cycle marine battery, and never discharge it below 50% if it's rated capacity.
     
  12. LDC3

    Active Member

    Apr 27, 2013
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  13. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    Good feedback,
    Thanks everyone.
     
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