Peltier Cooler Box

[solissydney]

I spent a few hours making a cardboard cooler box for my Canon 5D. The Peltier, Max 5 Amp, I got out of a Travel Cooler model M4501 (a free give away from Dick Smith before Christmas) I just installed a small fan inside the box to circulate the air.
Today I tested the setup, See image. Ambient temp was 25 C. After 5 min it showed 20 C, after 10 min 18 C, after 15 minutes 16 degrees. Overall a drop of 9 degrees. I got some 20 - 25 mm thick Styro Foam from broken boxes at the Green Grocer I will insulate the box externally later. Cost of the project? $5.00 for the switch box.

[solissydney]

Having externally insulated the box using 23 mm Styrofoam, free from the Green Grocer, the cooling figures are as follows: Empty box, no camera inside.
Ambient temp was 20 degrees, it took 60 min to cool down to 12 degrees.

I then lined the box with copper sheeting and expected great things.
Ambient temp 28 degrees, box empty no camera, it took 45 min to cool down to 15 degrees. Forget about ten degrees or below using the Peltier from those coolers mentioned in my earlier post and, this box is tiny. Also, these temperatures are without any camera in the box. Inserting a camera would make the figures even worse.

[solissydney]

One solution, in part, would be to use a slower fan inside the cooler box. Think of the air conditioner in your car. On highest speed you get quick cooling down. On slow speed you get max cooling. There is is only so much coolth to distribute.

[solissydney]

One further thing, in regards to frost on the cold face. Someone mentioned that it only occurs at 0 degree. I got solid frost at 12 degrees. If the box is cold enough you get solid frost, if not, you get condensation.
In winter the windscreen on my vehicle frosts over at four degrees.

[MrB]

In my best mythbuster voice.. "well there's yer problem"

The frost is insulating the cold face.
The air in the box may be 12deg but the cold face is below zero, hence frost.
A small computer fan, 40mm or something like that, will keep the cold face warm enough(by cooling the air blowing over it) to stop it frosting...
Even better would be to mount a small heatsink on the cold side with the fan mounted to that... a smaller version of whats on the hot side.
Have fun ;)

[solissydney]

You mean instead of sucking off the cold face the fan should blow on or over the cold face? I am presently testing that Simon.
Thanks
Ken

[danielsun]

Very interesting work in progress Ken.:thumbsup: Keep us updated on the results. :)
And possibly a good solution there Simon.;)


Cheers Daniel.

[solissydney]

The testing was done with a fan on the cold face. Unable to fit my present box on my focuser I have just made up another cardboard box 25 by 13 by 9 cm. Not yet insulated the temp in the empty box dropped from 25 deg to 15 deg in 15 min without any frost on the cold face. My intention is to insulate the box externally with, I hope, 10 mm foam If I can find some and also insert the small heat sink on the cold face and attach the fan to that like Simon suggested. With the camera in the box, turned on, it took 20 min to reach 14 degrees. It appears that with this kind of a setup with frost forming on the cold face I have to be contend with temp around 15 or a little less. (By the way, inserting the copper lining in my earlier cooler box made little or no difference to the drop in temp. I will not be doing that in the new box.)
Will keep you informed Daniel
Ken

[Garyh]

Hey Ken, instead of having a heatsink on the cold side why not move the TEC to the bottom of the box under the camera and use some copper plate to attach from the TEC to the tripod adapter? That way you are using the camera frame to act as your cooling plate right where you want it, inside your camera! Have done this with my other cameras and even without a box around the camera I usually get 7-8c cooling inside the camera. Should double that inside a box, even more. Have you checked Gary Honis website for his cooled 450D
He uses the aluminum box as cold plate more or less. The camera would also be attached to the aluminum by the tripod socket also.
http://ghonis2.ho8.com/rebelmod450d16c.html
cheers

[solissydney]

Thanks Garyh.
I did have a look at his page. What I missed what his "see next page". and of course his third page. I thought something was missing. Now it makes sense to me.
Did you have to inform me of this?? Now I have to alter the box again, drats!

Thanks Garyh, will keep you informed
Ken

[solissydney]

Garyh.
Do you mean just onto the screw thread only on the bottom of the camera?. Brilliant .
Ken

[Garyh]

No probs Ken, might have to put a box around mine as yet. So will be interesting how it goes.
cheers

[danielsun]

Ken , if you are chasing some insulated 10mm styrafoam board there is a company called foilboard aust that insulate houses,
http://www.foilboard-insulation.com.au/ or if there are any housing estates going up nearby a good chance that you may find some off cuts.
I used them a few times back when i was building.

Cheers Daniel.

[solissydney]

Thanks for your tip Daniel
Ken

[solissydney]

Garyh, your method did not work for me and my camera. I tried using a tripod screw which has a 20 mm flat head on it. I saw no drop in temp at all.
Ken

[danielsun]

Guys I'm at the beginning stages of experimenting and I am wondering how the #%* are you guys getting the peltier so cold to temps around zero?
I can only seem to get mine down to aprox 19deg. I have tried larger power supplies (12 amp) + bigger fans with bigger heat sinks sucking and tried blowing on the hot and cold sides but not much good.
I am obviously missing something here.


Cheers Daniel.

[solissydney]

Give us details of what you do and pics if possible Daniel.
I can get mine down to 15 degrees on a regular basic. That's all.
I just purchased some 0.5 mm AL. and will make a box and insulate that and test it.
Ken

[tlgerdes]

another thing i was reading was that the temp diff can be vastly effected by humidity ie high humidty = less temp drop.

[Garyh]

That`s a bummer, I could get 7-8 degrees drop on both cameras. Maybe the full size cmos generates much more heat?

Daniel, I tested my setup and I could achieve around 24 degrees below ambient. It was 27c and the TEC cold finger was 3-4c.
Depends on what you are trying to cool? as the size or mass you are trying to cool?
cheers

[solissydney]

Tec cold finger 3 - 4 degrees????

I have always been testing the air in the box, never the cold finger
Ken

[danielsun]

Hi guys,
I have been testing the temp with the sensor directly on the back of the peltier module(cold side of course) then I made a copper finger with the temp sensor on that though it was 32deg and it dropped to 19 deg.
From what i had been reading on other DIY's I was expecting it to go down to at least 0 or 2 degrees.

Cheers Daniel.

[solissydney]

With my cardboard box now lined with 0.5 mm AL. I am now only able to cool the interior of the box to 20 degrees. Without the Al. it always drops down to 15 degrees in 15 min. Don't ask me about the conductivity of the Aluminium. No one seems to know. So, looks like it is back to cardboard only.

Ken

[mill]

How weird :question:
My tec on the inside of the box has ice on it when it is 25C.
But then again i am a bit of a smart a$$ :P
When you build a peltier box you just make it bigger so you can put some special ice bags in it that have been frozen to -15.
I have something here that can be frozen to twice colder then dry ice.
So that is -190C :eyepop::eyepop:

See here http://cgi.ebay.com.au/10-Techni-Ice-Ice-Box-Esky-Reusable-Dry-Ice-Gel-Packs_W0QQitemZ250560189092QQcmdZVi ewItemQQptZAU_Backpacks_Hydration?h ash=item3a568d12a4

You can cut them in nice blocks and are good for when the fridge stuffs up.