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Old 06-08-2007, 08:10 PM   #1
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Peltiers

So now that I got my scanguage I'm truely amazed how turning on my headlights, or cranking up the fan can affect FE!

So I heard someone mention running a peltier kinda in reverse. Well at least not for heating and cooling like I've normally heard of them used for.

The Idea is simple. When electricity is applied to a Peltier device 1 side gets hot, 1 side gets cold. In reverse, say you attach to your exhaust, 1 side gets hot, and the other side under your car I would think would get cooled as you drive. This difference in temperature would create electricity. Generating 50W at 12v is enough for me to see a measureable difference since thats why my headlights use.

So I came across this site after some research, and holy cow! These guys have done it!

http://www.hi-z.com/websit07.htm

These guys made 1kW, but they say it only gained 3-5 hp which seems low to me. They also used 72 peltiers which they sell for $124 a pop, so not exactly cheap...

http://www.hi-z.com/Hi-Z.Brochure.2006.pdf

Also take a look at their brochure
That clamp on TEG looks perfect!!

What are your guys thoughts? How much temp difference could we get from a car exhaust??

I'm in Canada man! I imagine a huge difference in temp in the winter! It would be perfect you generate more power in the winter to compensate for richer fuel air mixture in the cold air!
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Old 06-09-2007, 01:14 AM   #2
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Hello -

This sounds like the thermoelectric stuff :

Someone has got to do this.
http://www.gassavers.org/showthread....thermoelectric

I think the issue was the cost of putting it in practice.

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Old 06-09-2007, 11:29 AM   #3
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This is the idea of the future (when thermoelectric generators get cheaper).

My plan (when I start my next project - I need to buy another car soon due to moving) is to get a leisure battery, and voltmeter, and put it in the boot. This can then be kept charged up by a 40/80W solar panel (a bit expensive) placed under the back window. During the daytime, the solar panels will 'assist' the alternator, while at night time, the leisure battery which has been kept fully charged can be used to run the car.

THis would require a lot of switches though - unlike peltiers which would work at night as well
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Old 06-10-2007, 06:26 PM   #4
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Well...some of the prices don't seem too bad...

http://customthermoelectric.com/tecs...FSnKggodTmnntg


24.0A / 226.1W / 15.2V @ 60C for $39.50 ... almost kinda tempting to put this in the engine compartment near the exhaust (on the fender well) and let it do passive charging of the battery. I guess the only thing one would need to do is put some sort of "trip" on it so it wouldn't start to reverse when the engine is cold. Seems a LOT cheaper than PV... Might be worth putting a few in the attic during the summer and let it run fans to cool the attic.
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Old 06-10-2007, 10:02 PM   #5
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the specs for these things will blow your mind away if you try to figure out how to make them perform like that in real life, I know they work, I've seen the stove top fans and so on that use them, but you really do need one side hot, and one side cold, not cool, but cold for it to meet most of the magical numbers, then you get in to radiators, and stacking enough of them close enough to a hot part, like the exaust, without over heating them of course.
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Old 06-11-2007, 12:18 AM   #6
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rvanengen and Ryland -

How about this? Attach one side to the top of the engine block and the other to a "radiator" sticking out of the hood? :

Attachment 561

At least in this case there would be a big temperature difference on cold days (wind chill factor). As long as the aerodynamic penalty doesn't outweigh the energy gain, this would be a win.

Anyhoo, it will be fun to watch this technology mature.

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Old 06-11-2007, 06:20 AM   #7
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There are lots of things that have stopped me from looking into TGs for my truck:

Cost.

A TG with 12-14 volts requires hundreds of individual junctions in series. If any one junction fails, then the TG will fail, and I'll be out about $1,000.

TG's require hot side temperature control to prevent frying.

TG's generate current as long as heat is supplied. A "charge controller" is needed to prevent overcharging (and destroying) the battery. (alternators use a voltage regulator to control coil current, perhaps 4-5 amps. A TG charge controller would need to switch 50 - 100 amps on and off.

As usual, the devil is in the details.
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Old 06-11-2007, 08:15 AM   #8
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Quote:
Originally Posted by Sludgy View Post
There are lots of things that have stopped me from looking into TGs for my truck:

Cost.

A TG with 12-14 volts requires hundreds of individual junctions in series. If any one junction fails, then the TG will fail, and I'll be out about $1,000.

TG's require hot side temperature control to prevent frying.

TG's generate current as long as heat is supplied. A "charge controller" is needed to prevent overcharging (and destroying) the battery. (alternators use a voltage regulator to control coil current, perhaps 4-5 amps. A TG charge controller would need to switch 50 - 100 amps on and off.

As usual, the devil is in the details.
Why would you need a controller for each TG?
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Old 06-11-2007, 10:33 AM   #9
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Quote:
Originally Posted by Sludgy View Post
There are lots of things that have stopped me from looking into TGs for my truck:

Cost.

A TG with 12-14 volts requires hundreds of individual junctions in series. If any one junction fails, then the TG will fail, and I'll be out about $1,000.

TG's require hot side temperature control to prevent frying.

TG's generate current as long as heat is supplied. A "charge controller" is needed to prevent overcharging (and destroying) the battery. (alternators use a voltage regulator to control coil current, perhaps 4-5 amps. A TG charge controller would need to switch 50 - 100 amps on and off.

As usual, the devil is in the details.

Why would it need hundreds of junctions? Heck, you can buy a single one and connect it to the battery and let it charge when the car is running, or even make it a one-way circuit and let it run as long as there is enough temp differential??

Not sure I understand why you need temp control either...sounds like planning where it is placed would be good enough. I know in my engine compartment, I could easily place one on the fender *near* the exhaust manifold and put the "cold" side facing away (even put the heatsink) sticking through into the wheel well for cooling. It shouldn't get hotter than 200C.

Once again, I admit to be VERY new to this technology, but it seems simple enough to me??
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Old 06-11-2007, 03:35 PM   #10
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The max voltage for each junction is low. You'd need a lot in series to make 12 or 14 volts.
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