1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Peltier Power generation....

Discussion in 'Renewable Energy' started by Stan Smale M.D. (stan), Jul 25, 2014.

  1. Stan Smale M.D. (stan)

    Stan Smale M.D. (stan) New Member

    Joined:
    Jul 25, 2014
    Messages:
    2
    Likes:
    0
    Has anyone (in this group) tried using Peltier devices for power generation ?
    It is an interesting experiment... Hook up a load (say 1 - 10 ohms) across a
    Peltier, then place a temperature differential of 60-80 celcius across the device.
    Keep the maximum temp below 125 celcius, or so. Measure the voltage across
    the load (use 10 ohms load here), then measure the output current (1 ohm load).
    My experience was such that a single Peltier generated 750 ma current, with output
    voltage about 0.4 - 0.5 V // or with a larger load resistance, a single Peltier may generate
    0.75 - ~1.00 V with current of about 100 ma. This will probably vary, depending on the
    make and size of the device used. Mine was surplus (manufacturer ?), dimensions
    1.6 x 1.6 inches. A caution; don't go too high on the hot side of the device - they seem to be
    assembled (at least partially) with solder joints (wires). A little too much heat, and the
    output drops to zero, when a wire falls off..... Something else interesting to try is to make
    measurements, then reverse the hot/ cold sides, repeat measurements.
    A thought... maximize your solar panel output; mount peltiers behind each solar cell,
    effectively extending the energy conversion range down into the far infrared. Needless to
    say, good heat conduction 'mating' of surfaces is a must. I found that, cooling the 'cold'
    side with a water-feed aluminum heat sink, using cool to cold water ( say, from a stream,
    if this system supplied a mountain cabin), works well; temp 5 - 15 celcius. The 'hot' side
    could be heated by another water feed, collecting the water directly from a solar water
    heater (temp 65 - 85 celcius). Supposedly, power output increases, as temp differential
    increases... until solder or bismuth telluride flows.... we all have limits.

    Of interest, Voyager I and II appearently used these for power source, with a slowly
    decaying radioactive source supplying heat. Also, I believe, may have been a backup
    power unit for the Mars rovers (solar cells primary source).... don't qoute me on the
    last; info about 4th hand...


    Addendum : just repeated measurements on another Peltier (same size, same unknown manuf ?)....
    Peltier mounted on large Al heatsink, which I placed finned part in water/ ice bath. I heated water in
    flat-bottomed pan to boiling, then placed pan/water against opposite side of Peltier.
    Measurements : Voltage directly across leads of Peltier : 2.35 V
    Current (measured as a dead short with ammeter, i.e. no load resistors in circuit) - 0.95 Amps

    Please realize that these are NOT concurrent measurements; in other words, I did not see 0.95 amps with
    a voltage output of 2.35 V. When current measured, voltage will drop, if dead short measurement made;
    and when voltage measured with high input impedance meter, very little current drawn at that time. I've
    thought about mapping I vs V curve, but haven't done so yet. This would show what the maximum Power
    output of the Peltier could be (at the delta Temp used).

    Enjoy !
    Stan
     
    Last edited: Jul 25, 2014
  2. cowboybob

    cowboybob Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2011
    Messages:
    3,026
    Likes:
    477
    Location:
    James Island, SC
    Welcome to ETO, Dr. stan!

    Played with small ones, hooked to SMPS boost devices so I could get usable (5.0 or 3.3 VDC) outputs. Pretty nifty devices for powering remote sensors utilizing ambient heat (from a motor, for example). Outstanding for moderately slow charging of super caps.

    Works best when the data needed can be sent periodically (burst mode). Efficiencies somewhat mimic solar devices (not great, but adequate to the task.

    Biggest negative (to me) is the heat sinking (or temp differential) issue (as you described).

    Are you new to electronics or have you been interested for some time?
     
  3. ronv

    ronv Well-Known Member Most Helpful Member

    Joined:
    May 30, 2010
    Messages:
    4,725
    Likes:
    488
    Location:
    Tucson, AZ. USA
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. simonbramble

    simonbramble Active Member

    Joined:
    Nov 22, 2010
    Messages:
    430
    Likes:
    63

    The problem with Peltiers is their incredible small output voltage. LTC do a boost converter to take a Peltier and convert it to something useful:
    http://www.linear.com/product/LTC3108-1
     
  6. kubeek

    kubeek Well-Known Member

    Joined:
    Mar 11, 2006
    Messages:
    1,491
    Likes:
    186
    Location:
    Prague, Czechia (not Chechnya)
    ONLINE
    Just yesterday
     
  7. Pommie

    Pommie Well-Known Member Most Helpful Member

    Joined:
    Mar 18, 2005
    Messages:
    10,024
    Likes:
    317
    Location:
    Brisbane Australia
    Here's an interesting article from 1993 on thermal electric generators. Thought it might be of interest to anyone trying this.

    Mike.
     

    Attached Files:

    • teg.pdf
      File size:
      28.1 KB
      Views:
      274
  8. tcmtech

    tcmtech Well-Known Member Most Helpful Member

    Joined:
    Feb 22, 2009
    Messages:
    6,659
    Likes:
    429
    Location:
    Sawyer, North Dakota, USA
    I made something like this a few years ago for a local elementary classes science lab. I used an old 20 watt Peltier unit from some old computer CPU cooler and two heat sinks.

    The concept was that by placing the smaller lower heatsink in a bowl of hot water and a handful of crushed ice or snow on the larger upper heatsink it would put out the same power as a typical D size battery for several minutes. At load it would carry up to about 1 amp at ~1.5 volts which in elementary kids views was more than a enough to run little lights and motors off of it! :cool:
     

Share This Page