thermoelectric voltage and amperage test now visable

[mans]

here is a copy and paste from the seller of the item. they are on ebay. quote:

Yah, on my first attempt I had the stove so hot that it melted the solder on the TE almost immediatly. I opted to use a heat gun for convenience. I'm not an engineer, but I stopped it at 3.6 volts...I think it was topped out but my very bad set up was slipping so it seemed like a good time. The motor had 3.5 ohms resistance, so, I think that is 1 amp right? Here's a You tube of my experiment

http://www.youtube.com/watch?v=bI_tg3oLuZE

end quote from seller.
the seller made this video for me.

I am not sure about the resistance he mentions which he says show 1 amp. are his calculations correct?

linky: 100 pcs for $3 each.http://www.ebay.com/itm/?cmd=ViewIte...%3D%26_fvi%3D1

if anyone can verify that his calculations are indeed correct and this cell is producing 1 amp and 3.5 volts like he says then he has got a great product and quite affordable too. but is this correct and genuine?

[jakobnev]

When the motor spins it develops a counter EMF so the current will be less.

[mans]

guys?

if this video wasn't from a seller who wants to sell them I'd go ahead and try a few. it may be genuine, but i'd love to hear some feedback before I try a few.

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.

now ten such sets (total 40 cells) would be 14.4V and 40A. perfect to keep a small car's battery charged.

anyone have some electrical knowledge on such a topic?

[gone-ot]

...the BIG question is: what was the temperature of the thermopile? How HOT was the air from the hairdrier?

AMPS = VOLTS / OHMS

...from his words: 3.6 Volts / 3.5 Ohms = 1.03 Amps, but as mentioned above, the motors' Counter-Electro-Motive-Force (CEMF) is gonna lower the usable current below the simple 1.03A source value.

[mort]

Originally Posted by mans

guys?

if this video wasn't from a seller who wants to sell them I'd go ahead and try a few. it may be genuine, but i'd love to hear some feedback before I try a few.

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.

now ten such sets (total 40 cells) would be 14.4V and 40A. perfect to keep a small car's battery charged.

anyone have some electrical knowledge on such a topic?

Hi mans,
The seller does say replace or refund for any reason, so I'll trust the video. This thermocouple, at full power, uses 127 watts to move about 80 watts. Also, the performance graph shows that at 70 C across the device, the cooling power is equal to the heat leaking from hot to cold. So assuming you could keep the "cold" side at boiling, 100 C, and the hot side at 25 C There would be 80 Watts of heat leaking through and 80 Watts being converted. The best thermocouples can convert under 10% of the heat flow to electricity, so that would be 8 watts. I'd say 3.5 watts is possible considering these are commercial devices. And the demonstration is a heat gun and the back apparently clamped to a copper plate.

If the efficiency of these is 5%, then to deliver 40 A at 14 V you need to convert 11 KW, including leakage gets to 22 KW. Which is about all the heat in the exhaust at cruise. Also this is about the amount of heat dumped by the radiator. So you'd need a big heat sink and lots of air flow.
-mort

[BrokeFix]

I can't post links because of my post count, but search 'campfire generator part 4' on youtube.

I would be interested in seeing a similar system using the hot input of this device rigged to the car's coolant line and the cold input connected to a heatsink of some sort. Seems like a cheap way to recover some waste heat, unless I am missing something.

[serialk11r]

Originally Posted by BrokeFix

I can't post links because of my post count, but search 'campfire generator part 4' on youtube.

I would be interested in seeing a similar system using the hot input of this device rigged to the car's coolant line and the cold input connected to a heatsink of some sort. Seems like a cheap way to recover some waste heat, unless I am missing something.

The car's coolant line won't be hot enough to generate much electricity, especially because thermoelectric generators have horrible efficiency. Where they should go is the exhaust, but generators that can handle exhaust temperatures aren't commercially available to the best of my knowledge.

[kurzer]

Originally Posted by mans

if each cell can put out 3.6v and 1 amp, then 4 cells in series would be 14.4V and 4A.

this isn´t true, sadly.
P=U*I
3,6V*1A= 3,6W
3,6W*4= 14,4W
14,4W/14,4V=1A

the current in series dosn´t add up. it´s the same with batterie packs.

[BrokeFix]

Originally Posted by serialk11r

The car's coolant line won't be hot enough to generate much electricity, especially because thermoelectric generators have horrible efficiency. Where they should go is the exhaust, but generators that can handle exhaust temperatures aren't commercially available to the best of my knowledge.

From what I've read, an average coolant temp seems to match with the sellers max temp for the TE devices.

Not too sure about the efficiencies of the individual units, but judging by the campfire generator video, one could expect 2 amps @ 15v from 16 units. But what I know about electronics I can write on the head of a nail.

Still it's looking like it may not would be worth it for a $100 price tag (the price of 20 units + shipping)

[Ken Fry]

Originally Posted by mans

guys?

it may be genuine, but i'd love to hear some feedback before I try a few.

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.

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.

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.