# controllers best way to mount



## Guest (Jun 9, 2011)

Having the heat sink properly attached to the large flat surface of the controller and having a fan that will blow air over the fins you can pretty much mount it any way you like as long as you have good air flow around the setup. I had mine upside down and sidways. As long as you have the sink and fan you should be fine. But you must have the sink mounted properly. Be sure both surfaces are flat before you put on your thermal grease. Don't use too much but be sure you cover the entire area. If you want you could put a fan so it blows on the casing too but the main heat transfer is on the bottom through the sink. That is the heat you need to move away from the controller quickly. 

Pete


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## 9852 (Jan 17, 2010)

great advise pete, now what about sanding off the paint on the bottom of the controller, i did that to one of the curtis casings that i have here just to see how it would look, and with the paint gone it should give better contact with the sink, what do you think?


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## gojo (Feb 1, 2011)

billhac said:


> great advise pete, now what about sanding off the paint on the bottom of the controller, i did that to one of the curtis casings that i have here just to see how it would look, and with the paint gone it should give better contact with the sink, what do you think?


Maybe, but a related topic would be colors that radiate the most heat. I would have thought silver would give off more heat, but from what I have found is; experiements indicate a black surface will radiate the most heat.


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## Guest (Jun 10, 2011)

So what colors actually radiate heat? I now colors that absorb or reflect but in the case of the heat sink the paint would be trapped between the two pieces. Now it could be that the paint is designed like the thermal grease and allow heat to transfer through the paint but not likely. I removed the paint on my Kelly then mounted the controller. It will be just fine. No one said that the paint is special. I have asked. Not likely that the paint is any thing other than your el cheap o paint. 

The choice is yours. I can only say colors help either absorb or reflect.


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## 9852 (Jan 17, 2010)

yea its easy enough to remove, i was wondering if you removed the paint on your new kelly controller, now i know


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## Guest (Jun 10, 2011)

Yup, sure did. Looks good as well. No paint to disrupt the transfer of heat. 

http://greenev.zapto.org/GreenEV/GreenEV/Kelly_Control_Sink.html


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## drgrieve (Apr 14, 2011)

gojo said:


> Maybe, but a related topic would be colors that radiate the most heat. I would have thought silver would give off more heat, but from what I have found is; experiements indicate a black surface will radiate the most heat.


This is correct black is the best color to radiate heat. Silver is fact doesn't radiate at all. Hence with a air gap; silver backed insulation installed silver face down stops most radiant heat through the roof.

However in the controller situation we are dealing with conducted heat transfer thus the color is meaningless.

Another way to test it. Place a stainless steel bar in the sun. Put your hand near it, you shouldn't be able to feel the heat radiating to your hand. Touch it, ouch!

Now my question is, does this mean a heat sink (if silver color) without air movement does nothing?? I would guess so. In this case you would need to paint the heat sink black if you have no air movement.


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## Guest (Jun 10, 2011)

The heat sink is not getting the heat because the sun. In that case what is happening is you get absorbed heat then it will radiate back out. If you don't paint it or paint it silver then put it in the sun the part will reflect a larger amount of heat but will still radiate that heat back out. 

The controller is getting its heat from within an enclosed structure and no light can enter. So in a lightless room even white is black. 

Colors only absorb or reflect.


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## Guest (Jun 10, 2011)

You can have paint that has insulating properties that will allow heat to be retained. If paint is not insulating then the heat has an easier time to radiate out. Again, color not meaning a thing. So under your hood you paint your engine block black because they say it helps dissipate heat better. Bull. Paint it any color you want. Yellow, Pink, Blue. It may be good to use a paint that can handle high heat so it does not flake apart from the heat. Nothing to do with helping keep the engine block cool. 

Do we need to do a science show and tell for this too?


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## 9852 (Jan 17, 2010)

well this is why i started this thread, in my neon i went through several controllers, and would like to do it better this time. all great opnions


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## Guest (Jun 10, 2011)

Bill,

What controller do you have now? 

Pete


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## 9852 (Jan 17, 2010)

its a home brew, i modeled it after the open revolt (power section) but i designed it to fit a "curtis style" casing. i will be posting some pictures of it in the next week or so, just waiting for 1 more piece to come in the mail, then it will be ready. i have some good bench test results but im not putting much faith in those, the test will be installing it on the car and driving it.


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## gojo (Feb 1, 2011)

gottdi said:


> So what colors actually radiate heat? I now colors that absorb or reflect but in the case of the heat sink the paint would be trapped between the two pieces. Now it could be that the paint is designed like the thermal grease and allow heat to transfer through the paint but not likely. I removed the paint on my Kelly then mounted the controller. It will be just fine. No one said that the paint is special. I have asked. Not likely that the paint is any thing other than your el cheap o paint.
> 
> The choice is yours. I can only say colors help either absorb or reflect.


The theory is, dark colors radiate a larger range of waves.


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## piotrsko (Dec 9, 2007)

my $.02: back in the day at Huge aircrash space and comm, we painted anything we wanted warm, black, anything that was a radiator was clear, anodized (salt spray requirement), polished or bare metal.


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## GizmoEV (Nov 28, 2009)

billhac said:


> ...knowing that heat rises...


I know this is a little late to this thread but the above statement bugs me. It is not true that heat rises. In a fluid, the warmer fluid is less dense than cooler fluid making the warmer fluid more buoyant and causing it to rise. In conducting of heat, gravity has absolutely no affect. It doesn't matter direction is "up" it will flow equally in any direction. If you are using the convection of air to cool a heat sink then as the heat sink warms the air then the warmer air will rise. Note that the air is warmed much more from conduction than through radiation from the heat sink.

As for painting, a flat black painted aluminum canister will cool faster than an identical one which is not painted. The difference isn't very much, however. Probably the best would be a black anodized heat sink than risking getting too thick of paint on one by painting it and negating the color (or lack of it really) benefit.

Both of the above were demos and/or experiments I had my HS physics students perform.


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## 9852 (Jan 17, 2010)

GizmoEV said:


> I know this is a little late to this thread but the above statement bugs me. It is not true that heat rises. In a fluid, the warmer fluid is less dense than cooler fluid making the warmer fluid more buoyant and causing it to rise. In conducting of heat, gravity has absolutely no affect. It doesn't matter direction is "up" it will flow equally in any direction. If you are using the convection of air to cool a heat sink then as the heat sink warms the air then the warmer air will rise. Note that the air is warmed much more from conduction than through radiation from the heat sink.
> 
> As for painting, a flat black painted aluminum canister will cool faster than an identical one which is not painted. The difference isn't very much, however. Probably the best would be a black anodized heat sink than risking getting too thick of paint on one by painting it and negating the color (or lack of it really) benefit.
> 
> Both of the above were demos and/or experiments I had my HS physics students perform.


so you are saying that it makes no difference which way the controller is mounted. this is why i asked this question, i was thinking if i mounted the controller on the assembly upside down with a heat sink and a fan on the base it would help dissipate heat better, but you think it really dont matter right side up or upside down? im not sure i agree with that, but what do i know, hense asking the question.


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## GizmoEV (Nov 28, 2009)

billhac said:


> so you are saying that it makes no difference which way the controller is mounted. this is why i asked this question, i was thinking if i mounted the controller on the assembly upside down with a heat sink and a fan on the base it would help dissipate heat better, but you think it really dont matter right side up or upside down? im not sure i agree with that, but what do i know, hense asking the question.


That is exactly what I am saying unless you are going to rely on convection of the air to cool it. Too many people learn that "heat rises" when the full statement is warm air rises. As far as *conduction* is concerned, orientation doesn't matter one bit. If you are relying on *convection*, then orientation does matter. The question comes down to how are you removing heat from the heat sink? If you have fans on it then, as Pete said, it doesn't really matter. The fans will easily overpower the convection "pressure." Don't forget that there may be a significant amount of air movement around the controller while driving anyway. This will seriously disrupt the convection currents and will either help or hinder cooling.

If Pete wanted to use convection instead of the fan he has on his controller then it would be better to rotate his controller 90° to gain the best cooling. Note, as he pointed out, the connection of the controller to the heat sink is more critical than orientation.

Here is his pic again:


gottdi said:


>


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## 9852 (Jan 17, 2010)

well ok then, im convinced, i will just make sure that the heat sink is mounted correctly and it will have a fan. thanks for everyones help, when its done i will post some pictures of the install.


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## jehan12413 (Feb 4, 2010)

It's called black body radiation and the theories relate to an abject absorbing and emitting radiation. Carbon is the best (within 3% of theoretical). An oversimplified explanation would be that as the temperature of an object increases so does the wavelength that it emits ( ie heated steel red then orange then white ). But at the temperatures we are discussing here all the radiation is in the far infrared range (heat) not visable. In the far infrared most paints appear black which is an excellent emitter and absorber. Silvery metals on the other hand reflect visable and infrared. What this means is that if the heatsink is painted it will radiate far more than bare metal. The paint will create a slight insulating coating but this is neglegeable compared to the considerable increase in radiation. Use a wood stove as an example , they are black for a reason. The sections of stovepipe which are silver radiate much less heat than the black ones. Flat black is used because it's a thinner coating than one of the thicker glossy paints. 
I would remove the paint on the back side of the heatsink because there you are concerned with conduction not radiation and I would very lightly paint or annodize the side with the fins.


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## dtbaker (Jan 5, 2008)

anodizing is hard to do at home.... matte black hi-temp spray paint on fin side would help a little.... or if it is raw aluminum (unsealed), it might darken considerably if you spray on something mildly acidic like tomato juice or lemon juice.


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## Tesseract (Sep 27, 2008)

dtbaker said:


> anodizing is hard to do at home....


Aw, hell, Dan... anodizing isn't that hard to do at home. It's actually one of those surface finish processes that is eminently DIYadble.

The critical step - unsurprisingly - is to clean/degrease the aluminum first ("mag wheel cleaner" works very well) then *etch* it in a dilute caustic lye bath (10% NaOH). 

An especially good overview of the anodizing process is here: http://www.focuser.com/anodize.html

A useful calculator for determining the amount of current needed for a given area of aluminum vs. time in the anodizing tank is here: http://www.ndhsubmersiblescience.com/ano/720rule.html


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## dtbaker (Jan 5, 2008)

Tesseract said:


> Aw, hell, Dan... anodizing isn't that hard to do at home. ...o clean/degrease the aluminum first ("mag wheel cleaner" works very well) then *etch* it in a dilute caustic lye bath (10% NaOH).



yeah yeah yeah... caustic lye baths then power supplies in baths.... right up the alley of the average DIY.  


I would vote for paint or lemon juice for most!


d


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