thermocouple to a battery

[John Woodgate]

I read in sci.electronics.design that Bughuggger <bughuggger@aol.com>
wrote (in <20040323095914.28938.00000197@mb-m25.aol.com&gt about
'thermocouple to a battery', on Tue, 23 Mar 2004:

Perhaps a series of capacitors would
not waste too much energy between my thermocouple and battery,

You don't need capacitors: you battery is an excellent storage device.

or
perhaps when I look at the solar cell, I notice that with a small input
it creates a large voltage though small current. I think the
thermocouple creates a large current but small voltage. Tell me if I'm
mistaken.

You are not.

Causally speaking, what is the difference between the solar
cell and the thermocouple with equivalent energy input?

The real explanation would be very complex. Try this analogy. All
electricity generators and their loads form a circuit path that is
almost all downhill but has at least one step in it. The external energy
source pushes the electrons UP the step(s), and from there they run
downhill.

(This may seem like a 'baby's' analogy, but in fact it's quite close to
reality, in which the vertical dimension is energy rather than
distance.)

In the case of the solar cell, the step is tall, corresponding to a high
output voltage, so a given amount of energy can push only a few
electrons up it - and few electrons make a small current.

In the thermocouple, the conversion from heat to electricity occurs in
the wires, NOT at the junctions. The temperature gradients along the
wires create small steps, up which the energy can push lots of
electrons, so you get a low voltage but a high current.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John Woodgate]

I read in sci.electronics.design that Bughuggger <bughuggger@aol.com>
wrote (in <20040323100127.28938.00000198@mb-m25.aol.com&gt about
'thermocouple to a battery', on Tue, 23 Mar 2004:

Okay smartasses,

Not a good word to use when you are asking for help. I didn't get the
post you appear to be replying to, though, so your feelings may be more
or less justified.

I'll change my question. How do you convert amps to volts,
even if you don't care if it takes a year to charge your battery.

You can't, in the sense that I think you mean. Fred Bartoli told you how

to do it with a DC/DC converter, but it's a complicated process,
requiring a lot of knowledge of electronics. You'd do far better to stay
with the many-hundreds-of-junctions solution; it's electrically simple
and the mechanical part is easy to design, if not so easy to make.

In any case, if you use thick enough wires, you will get ample current;
it's getting the 15 V or so that requires the large number of junctions.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Bughuggger]

I've got an idea. The millivolts from the thermocouple could power a tiny
electronic motor to which was attached a u-shaped wire which revolved in
between two magnets. This would be a standard generator. A bit slow, but still
worthy.

Bughuggger@aol.com

 

[Bughuggger]

Speaking of thermopiles and power generation, is it possible to buy a
plutonium powered thermopile for generating electricity in remote
areas, or is this sort of thing limited only to the government?

Norm Strong

Try the v-shaped stirling engine with water in it which is powered by the sun.
Generates enough power to pump water, and is quite cheap.

Bughuggger@aol.com

 

[ddwyer]

In article <c3kdp8$92t$1@titan.btinternet.com>, Reg Edwards
<g4fgq.regp@ZZZbtinternet.com> writes

How do I make a thermocouple the same voltage as a battery to charge it.

========================

You need many hundreds of thermocouples all in series. And it will take hell
of a long time to recharge the battery.


Back in the old USSR there used to be a multi thermocouple fitting to

place on top of a paraffin lamp to power a transistor radio directly.
--
ddwyer

 

[TBFisher]

How do I make a thermocouple the same voltage as a battery to charge it. I
want
to do it with a copper wire, an iron wire, a magnifying glass, a small
chamber,
and the sun. To a 12 volt battery.

Also very interesting:

http://www.eneco-usa.com
Tom Fisher
BigD