Thermo electric USB Charger

[Junkie]

Here is the usb charger I built. It is an 138W thermo-electric module with an AMD PC heatsink. The output is 5V and up to 400ma to charge devices via usb as well as an output for powering other devices such as radio or Nicad Chargers etc. Originally I had it running off my precious ikea tealights but I've run out of those and the Chinese ones from Asda don't work, so I'm using a small DIY alcohol burner. The circuit I built my self to step the output from anything above 1.5V to 5V for the USB circuitry. I am going to try one of those fancy heat-pipe-do-it-all-and-save-the-world type heatsinks to see how it changes the output, when research budgets allow! Allot of people seem to think that more heat equals more power, but the heatsink is the most important part in my opinion!

http://1.bp.blogspot.com/_TAlhJmsRW4Y/SR9eeTb6arI/AAAAAAAAACE/Q0RKxwFTluA/s1600-h/TEG_FAN_1.JPG

^Cooling fan and circuitry.

http://1.bp.blogspot.com/_TAlhJmsRW4Y/SR9eYLTLaeI/AAAAAAAAAB8/qQbk8JimF7U/s1600-h/TEG_FRONT_1.JPG

^Front showing burner

http://2.bp.blogspot.com/_TAlhJmsRW4Y/SR9eSpqWTQI/AAAAAAAAAB0/CI0xU5qfgLA/s1600-h/TEG_USB_1.JPG

^ USB output

If the mods could make the images appear in the thead it would be appreciated but I couldn't get the HTML tags to work. There is more information and a video on my blog http://www.reukpower.blogspot.com/

[Nothing40]

Cool!

I've been thinking about some kind of small 'candle powered' generator of some sort for a while,I wasn't sure how the TEC idea would work out,so I was heading in the Sterling engine direction. We burn candles all the time,so even a small amount of power would be nice.

It's nice to know that the TEC/Peltier setup works!

I agree with you,the heatsink is a key point.The temperature difference is what counts.The cooler you can keep the 'cold' side,the more power it should make,up to a point,anyways.

[scottsAI]

Junkie,

As you know the peltier works off a temperature differential.

The colder the cold side and hotter the hot side the better.

The Fan to keep heat sink cool will draw more power than the peltier will produce!

Better go back to the sauce pan, fill it with cold water! Should work good for a while. Add cold water, as needed. ICE works best!

Beware of getting the peltier's too hot, appear to be assembled with solder.

I melted a set, just when it was giving a decent output.

I am assuming this is more of a science experiment? efficiency of the peltier is worst than poor.

Try using a chimney effect, have the hot air below come up in a chimney keeping it away from the heat sink and sucking air from the cold heat sink, might make things work better without a fan.

Have fun,

Scott.

[Junkie]

Hi,

   not sure what you mean about the fan drawing more power than the peltier will produce as it currently runs off the peltier and does keep it cool. Excess heat definitely does destroy these thing (I destroyed about 5 of them on the elctric hob) I am going to take it with me camping to see if it is any use :-)

[elt]

He means that the fan draws more power than it adds (by cooling) otherwise you would have created perpetual motion... not saying that you don't have to cool your device as is but that there's some point where you could use less heat and no fan and get more power (since the fan draws more power than it adds by cooling.)

Hope that helps... but very nice, that is a cool generator!

- Ed.

[Junkie]

Thanks. I see, I thought he was implying I'd stashed a battery pack in the heat sink to run the fan or something :-)

[scottsAI]

Junkie,

Ed had it right more or less. My CPU fans need more power than was being produced, would not leave anything left to charge with!

Small hand crank generator will be lighter and produce more power...

Or make a small 2 ft wind turbine...

To take camping.

Peltier was fun to play with, not practical.

Have fun.

Scott.

[ghurd]

Just a thought... I had some laptop fans.  12V at 40ma.  Ran from ~20ma at 6V.

They sure don't move much air.

G-

[scottsAI]

Ghurd,

Peltier as a power generator are like 1% efficient. (don't remember the exact number)

To get 5v at 400ma out is 2 watts, so need 200w of heat! (two candle power)

A good size fan is needed to cool the heat sink with that much heat.

Have fun,

Scott.