Stan Smale M.D. (stan)
New Member
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
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
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