how do I determine characteristics of unknown peltier module

[Lostgallifreyan]

Lostgallifreyan <no-one@nowhere.net> wrote in
news:Xns99B5AA307D4A2zoodlewurdle@140.99.99.130:

"Eric Braunhauffer" <ericbraun@hoffer.net> wrote in
news:mNFJi.919$Wo4.916@trnddc03:

I have an unknown (unmarked) peltier module. I'd like to determine
the characteristics of the peltier itself. The only things I know
about it are its size and the fact that it is drawing 6 amps at 12
volts. I'd like to determine it's output wattage if possible.
Anyone have ideas as to how I could do this?

Thanks,
Eric




A TEC made for 12V is probably set to be efficient at that voltage.
Such TEC's usually have a Vmax of about 14.5V, so assuming 2 ohms as a
basis for assuming 7.25 amps as Imax (you can test that briefly to see
if it's true) then consumed power will be 105 watts. Qmax will be
about half of that.

Should say in case unclear, Qmax IS maximum 'output power', it's the most
heat you can pump, such that cold side temperature matches hot side, when
hot side is on the best heatsink possible.

 

[Lostgallifreyan]

"Eric Braunhauffer" <ericbraun@hoffer.net> wrote in
news:mNFJi.919$Wo4.916@trnddc03:

I have an unknown (unmarked) peltier module. I'd like to determine
the characteristics of the peltier itself. The only things I know
about it are its size and the fact that it is drawing 6 amps at 12
volts. I'd like to determine it's output wattage if possible. Anyone
have ideas as to how I could do this?

Thanks,
Eric

A TEC made for 12V is probably set to be efficient at that voltage. Such
TEC's usually have a Vmax of about 14.5V, so assuming 2 ohms as a basis for
assuming 7.25 amps as Imax (you can test that briefly to see if it's true)
then consumed power will be 105 watts. Qmax will be about half of that.

 

[Eric Braunhauffer]

I have an unknown (unmarked) peltier module. I'd like to determine the
characteristics of the peltier itself. The only things I know about it are
its size and the fact that it is drawing 6 amps at 12 volts. I'd like to
determine it's output wattage if possible. Anyone have ideas as to how I
could do this?

Thanks,
Eric

 

On Sep 24, 1:02 pm, "Eric Braunhauffer" <ericbr...@hoffer.net> wrote:

I have an unknown (unmarked) peltier module. I'd like to determine the
characteristics of the peltier itself. The only things I know about it are
its size and the fact that it is drawing 6 amps at 12 volts. I'd like to
determine it's output wattage if possible. Anyone have ideas as to how I
could do this?

Thanks,
Eric

Pelteriers get hot on one side and cld one the other. They cannot go
below 0C. You need to heatsink them well and maybe cool the hot
side )with fan and heatsink)., Maybe having a fan runnning over it,
and the other side of the Peltier gets cold.They change polarity (heat
and cold) depending on the way you wire then up. I used 4mm perspex tp
make a decent heat exchanger. It is worth the effort.

 

[Hal Murray]

Pelteriers get hot on one side and cld one the other. They cannot go
below 0C.

What's magic about 0C?

I'm reasonably sure astronomers use peltiers to cool CCDs
much colder than that.

--
These are my opinions, not necessarily my employer's. I hate spam.

 

[Lostgallifreyan]

hal-usenet@ip-64-139-1-69.sjc.megapath.net (Hal Murray) wrote in
news:aZednZuMbtzUmGfbnZ2dnUVZ_o3inZ2d@megapath.net:

Pelteriers get hot on one side and cld one the other. They cannot go
below 0C.

What's magic about 0C?

I'm reasonably sure astronomers use peltiers to cool CCDs
much colder than that.

Yes, they do.

TEC's can have delta T of 67°C with a hot side clamped at 25°C, some as
much as 71°C, so around -45°C is usually possible with a tiny load, like a
sensor. The main reason to avoid going below 0°C is ice, if water vapour
gets in there, the expansion on freezing will easily break a TEC, but water
will damage the thermocouples anyway, so it should always be excluded.

 

[Roger Hamlett]

<brett4010@gmail.com> wrote in message
news:1190787047.179066.11580@g4g2000hsf.googlegroups.com...

On Sep 24, 1:02 pm, "Eric Braunhauffer" <ericbr...@hoffer.net> wrote:
I have an unknown (unmarked) peltier module. I'd like to determine the
characteristics of the peltier itself. The only things I know about it
are
its size and the fact that it is drawing 6 amps at 12 volts. I'd like
to
determine it's output wattage if possible. Anyone have ideas as to how
I
could do this?

Thanks,
Eric

Peltiers get hot on one side and cld one the other. They cannot go
below 0C. You need to heatsink them well and maybe cool the hot
side )with fan and heatsink)., Maybe having a fan runnning over it,
and the other side of the Peltier gets cold.They change polarity (heat
and cold) depending on the way you wire then up. I used 4mm perspex tp
make a decent heat exchanger. It is worth the effort.
Peltier devices, are effectively electrical heat pumps. They only get cold

on one side, if the heat being generated on the other is removed. This
heat comprises the heat being pumped, and the heat generated by the
Peltier itself. They can go way below 0C. There is a balance between how
much heat they can move, and the temperature difference between the two
sides of the module. Typically modules can achieve up to about 70C delta,
but at this, they are able to move almost no heat. Conversely, depending
on the size of the module, there will be a point where the temperature
difference reaches zero, for a given amount of heat to move (Qmax).
Typically a Peltier will draw about double the power, that they can move.
So, in the example, the element is drawing about 72W. This would be
typical of a module able to move perhaps 40W of heat at a 0C delta. Add a
heatsink, with a temperature rise of perhape 0.1C/W, fan cooled to the
'hot' side, and this will need to dissipate about 112W of heat in this
'worst case'. It'll then run up to about 11C above ambient. If you have
something that only generates 15W of heat, and attach this to the 'cold'
side, expect the delta C to be perhaps 45C, and the component to cool to
about 34C below the ambient. The actual delta will depend on the module,
but this would be a typical value for a module this size. The 'lowside'
temperature can be well below zero. There is nothing 'magic' for a Peltier
module about 0C. For even higher delta's, cascade two modules. Remember
though, that the 'hot' module, has to pump not only the original heat, but
the heat being added by the first module...
I have one sitting here on the bench, which is currently holding a couple
of semiconductor junctions at -40C. They are only generating about 1W of
heat, but to maintain this temperature (currently 62C below ambient), with
the two stage cooler attached, over 100W of power is being fed into the
cooler module, and the heatsink size reflects this...
The best way to 'characterise' the module, would be to measure the
temperatures on both sides of the junction, with known amount of heat
being applied to the cold side (resistor fed from a controlled voltage
source). You can then measure the delta T, for different power inputs, and
build your own graph for the behaviour of the module.

Best Wishes

 

On Sep 23, 11:02 pm, "Eric Braunhauffer" <ericbr...@hoffer.net> wrote:

I have an unknown (unmarked) peltier module. I'd like to determine the
characteristics of the peltier itself. The only things I know about it are
its size and the fact that it is drawing 6 amps at 12 volts. I'd like to
determine it's output wattage if possible. Anyone have ideas as to how I
could do this?

Thanks,
Eric

Eric,

Look at this... http://www.customthermoelectric.com/Peltier_analysis.html

It looks to be what you are looking for.

Cheers