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Originally Posted by mans
guys?
it may be genuine, but i'd love to hear some feedback before I try a few.
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It doesn't look like the seller is
intentionally being deceptive, but the time to freeze a small amount of water is meaningless. The output could be measured by the time to freeze a known, much larger, amount of water - or better, just the time to reduce the temperature of say 50 cc of water from 20 degrees C to 5 degrees c. This avoids the state change (liquid to frozen) which just complicates the calculation.
(The time recorded is mainly the time for the device to overcome it own mass [in other words, more energy is used in cooling the large mass of the unit itself than in the tiny mass of water]. )
As in so many YouTube videos, you can't tell if the experimental design is intentionally bad or if the experimenter does not understand good experimental design. A meaningful measure is (for use in a car) BTUs in and electrical energy out. The motor demo does not give any indication at all here: what's the actual output of the heat gun? how much of that output is absorbed by the device? Without evidence to the contrary, you could assume that the output of the heat gun is 1000 watts, and thus the input to the peltier device is 1000 watts (as a worst case). The output of the peltier device appears to be 3.6 volts and perhaps .2 amps (because running current would be much lower than locked rotor current) so about .7 watts. But how much of the 1000 watts blows right past the device? Probably most of it, but there is no way at all to know from the video.
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can anyone say if this video looks genuine? if each cell can put out 3.6v and 1 amp, then 4 cells in series would be 14.4V and 4A.
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The motor video looks genuine, but misleading. You would need to show both voltage and current, simultaneously. (Because the motor produces counter EMF, the current will drop as the motor speeds up). This would be obvious to anyone with an electrical background. Does the seller have such a background? Who knows? As soon as the motor is turning, the static resistance of the coils have no meaning.
If a cell were really putting out 3.6V and 1 amp, the four cells in series would put out 14.4 V and 1 amp, not 4.
You would need to do your own testing, and you would need to measure voltage and amperage at the same time.
Using engine coolant as the input and ambient air as the heat sink would require a pretty large heat sink and probably a blower. The energy used to run the blower would need to be deducted from the output.
If you can buy just one cell, they would be fun to play with and test: big enough to be able to measure with normal test equipment, small enough to not cost a lot.