# Controller Cooling



## TheSGC (Nov 15, 2007)

So while I await for my controller to arrive I have started to look at other EVs and how they cool their controller and I have found some serious lacking of cooling or description on how they do it. (I found a few EV with Alltrax controllers mounted to plexiglass.)

So my question is, where are you people mounting your controllers and how are you keeping them cool? I am fresh out of Aluminum plates (and money) but I can get steel plates pretty easily. I also have a water cooling heatsink thats a little smaller than the controller. 

My plan is to mount the controller to some sort of plate, with a thermal pad, and on the other side of the plate mount the water cool heatsink, which will be my heatsource for my EV.


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## madderscience (Jun 28, 2008)

here is a picture of my setup:

http://www.amphibike.org/images/640_controller_in_car.jpg

the heat sink came from ebay and is nearly a perfect fit for the curtis controller.

IMHO any heat sink should at least triple the area of the base of the controller; and an air cooled controller should be either mounted where air movement will occur while driving, or else fans should be attached to provide forced air cooling.

If you are going to stick with a flat plate, aluminum is a much better thermal conductor than steel is, so its worth finding an aluminum plate, but a finned heat sink would be better (and take up less space) if you can find one. If you can't find a large finned heat sink like I managed to, You might be able to make one up from a bunch of old computer CPU heat sinks and a flat plate to mount them all to, with countersunk screws, then attach the whole assy. to the controller.

And of course, use lots of thermal compound to ensure good thermal conductivity between the controller and the heat sink.


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## TheSGC (Nov 15, 2007)

I do have something like 18 Intel Xeon copper heatsinks the might make something nice. I will try eBay and the local machine shop for aluminum plates though.


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## Windy (Jun 27, 2008)

I found some nice heat sinks listed by Ctrsurplus.Com One they listed was 20"by14"by11/4 inches for a buy now price of $30.00. This is listed at their Ebay store.Hope this might help someone.Windy


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## TheSGC (Nov 15, 2007)

Windy said:


> I found some nice heat sinks listed by Ctrsurplus.Com One they listed was 20"by14"by11/4 inches for a buy now price of $30.00. This is listed at their Ebay store.Hope this might help someone.Windy


I'll go look those up. I was away for most of the day, but when I got home, my controller was sitting there!

I do have a plate chunk left over from my motor adapter that should suffice for a quick trip up and down the street, but a finned solution would be best.


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## Shanex-2 (Jun 7, 2008)

how hard would it be to liquid cool the controller? would it be practical?


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## TheSGC (Nov 15, 2007)

Shanex-2 said:


> how hard would it be to liquid cool the controller? would it be practical?


Water cooling would be the best way to cool the controller. I believe the higher end Zillas were water cooled. It's pretty simple, and in my case I am going to mount the controller to some sort of heatsink and then mount a water cooling brick to it and use that as heat for my EV.


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## Shanex-2 (Jun 7, 2008)

sweeeeet -where would you find something like that? Would you use a small boat buildge pump for circulation or something else?


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## Schmism (Aug 16, 2008)

the most common use for cooling blocks are computer chips. either the CPU, or GPU. 

but those water blocks are usually really small. 2"x2" or so.

in theory you could manufacture one to fit the top of the controller. you could pick up a CPU block to check out how they are made and scale it up.


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## Windy (Jun 27, 2008)

The cooling method I want to try is a combination using liquid as the primary and air as secondary. I have some 1/2 inch aluminum plate that I will mill slots that are 1/2 the diameter of 3/8 copper tubing in depth , there will be 2 matching plates. The copper cooling tubes will be placed between the matching plates in the slots and the plates secured together. A conventional one-sided finned heat sink will be attached to the backof the plate. Somewhere I was looking on line I found some heat transfer epoxy that would be good to insure good heat transfer from the plate to the copper cooling tubes. The fans for the finned heat sink would be controlled by a temp sensor so they would only turn on if needed. Even though milling is required this is a very simple procudure .Windy


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## Qer (May 7, 2008)

TheSGC said:


> My plan is to mount the controller to some sort of plate, with a thermal pad, and on the other side of the plate mount the water cool heatsink, which will be my heatsource for my EV.


That's my plan as well since I live in a cold climate and will need some way to keep the compartment warm. I can as well reuse the lost energy to something useful rather than waste more energy by generating heat in parallel. So I'm more or less planning to keep the original water loop in the car (maybe with a smaller cooler) and water cool the controller (se attachment of an example of what could be used), replace the original thermostat with some other means of controlling the loop and add some extra heat to the loop (in case it's really cold outside) like this idea:

http://www.diyelectriccar.com/forums/showthread.php/heater-17144.html

I'm also pondering if the battery pack should be included in that loop (they do generate heat as well), but I guess that might be making it a bit too complicated.

How much heat does the lead-accumulators actually generate while discharging...?


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## Shanex-2 (Jun 7, 2008)

Windy wont that cause a galvanic corrosion issue?


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## Windy (Jun 27, 2008)

THE dissimilar metal might be a problem but most heat exchangers for A/C systems use copper tubes with alluminum fins and show no ill effects even when exposed to the elements. Windy


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## Shanex-2 (Jun 7, 2008)

ah good point . I guess thats only an issue if it was put in salt water lol


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## Qer (May 7, 2008)

Shanex-2 said:


> ah good point . I guess thats only an issue if it was put in salt water lol


Or you live in a climate where they salt the roads to melt the ice...


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## EVMAN (Jul 26, 2007)

I don't run any cooling on my curtis 1231C. Never have. Never needed.
My vehicle weighs about 4200lbs w/batteries. 18 6V floodies, 65lbs each.
EVen on a hot sacramento summer day, I've never had my curtis go into thermal shutdown. Also, I would recommend against mounting the controller under any battery rack. Make the controller easily accessible from the top of the vehicle. Also, mount the controller close to the motor to make cabling short and neat. afn T


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## Gary Sconce (Oct 4, 2008)

I like the idea of liquid cooling, but I am dubious as to adding more that can go wrong with the vehicle. A good simple system would be completely convection driven with no pump or fan. Since heated fluid rises and cooler fluid sinks, this could be done.

Aluminum is nearly three times better at absorbing heat per kilogram than either brass or copper. An ample aluminum radiator linked to a large liquid bearing heat sink on the top of the controller would work. 

Water with antifreeze would be good as water absorbs over four times the heat per kilogram as aluminum metal heatsinks alone.

Fieros would be good for this as they have the tubes and radiator already run to the front from the back.

As I am going to use a 1970 Fiat 850 Racer I have to try to adapt any liquid cooling to the original radiator position behind the passenger seat in the rear motor compartment.

Anyone ever try to adapt a VW oil cooling radiator system? Just curious.


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## mattW (Sep 14, 2007)

I think the best application for water cooling would be in cooling the motor to give longer peak power times for hills etc..


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## Cimpso (Nov 10, 2008)

Gary Sconce said:


> .
> Aluminum is nearly three times better at absorbing heat per kilogram than either brass or copper. An ample aluminum radiator linked to a large liquid bearing heat sink on the top of the controller would work.


Don't want to stop on toes here, but copper is a far better conductor of heat, hence why most of the better CPU heat sinks and water blocks are made of it, for example.
http://en.wikipedia.org/wiki/List_of_thermal_conductivities


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## Tesseract (Sep 27, 2008)

Am I the only one here that thinks the manufacturer ought to be the one providing the heat removal capability, whether that be an integrated heat sink or even just a cold plate (as in the Zilla's)???

After all, the ability of a controller to meet (or even exceed) its claimed current handling spec depends on keeping its semiconductors (and capacitors) as cool as possible. Why a manufacturer would drop such a critical design aspect into their customers' laps is totally beyond me... That's just asking for early failures and complaints about poor performance/not meeting its claimed specs - hardly a good trade-off to save $50-$100 worth of heat sink...

Just my $0.02

Qer - It is very difficult to predict the temperature rise of any kind of battery, so much so that is often easier to simply embed a thermocouple and measure the actual temp. An excellent article discussing this is at: http://www.tms.org/pubs/journals/JOM/0101/Nelson-0101.html


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## Stiive (Nov 22, 2008)

Tesseract said:


> Am I the only one here that thinks the manufacturer ought to be the one providing the heat removal capability, whether that be an integrated heat sink or even just a cold plate (as in the Zilla's)???


Im with you 100%


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## jcsevparts (Dec 1, 2008)

Will a flat 3/4" plate of aluminum provide enough heat removing ability for a 1231C Curtis controller on an S-10 conversion? I have a large piece, so I can cut whatever size that would do the job......

What do ya'll think?


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## madderscience (Jun 28, 2008)

Quote from a curtis rep in response to my question as to recommended heat sink design for a 1231C:

"We do not have a recommendation for minimum heat sink area. We simply recommend making it as large as practical. A plate with twice the footprint of the 1231C should be fine. Use a thin coat of thermal paste between the controller and the plate. A metal to metal contact is best for heat transfer. The paste is there to fill minor voids. Note that there is at least one finned heat sinks available online form some non-Curtis source."

Its really the surface area, not the thickness that counts (provided that the plate is not too thin). The surface area is what allows heat dissipation.

I am using a finned heat sink that has the same footprint as the controller itself but with the fins it roughly triples the surface area. 

Personally I'd think a 1/4" plate is fine. 3/4" is probably overkill.

Of course, also locate the controller in a high airflow location, either where road wind will hit it, or add a couple of fans.


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## jcsevparts (Dec 1, 2008)

I could take the 3/4" plate and cut some fins in it 1/2" deep, do you think that would help?/work? Maybe with a carbide blade on a table saw?.....


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## madderscience (Jun 28, 2008)

sounds like a lot of work  but that would certainly increase the surface area.


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## Wirecutter (Jul 26, 2007)

jcsevparts said:


> I could take the 3/4" plate and cut some fins in it 1/2" deep, do you think that would help?/work? Maybe with a carbide blade on a table saw?.....


 In short, yes, this could work. Many times I've used a carbide tipped blade in my table saw to cut aluminum up to 1.75" thick. (I also wear earplugs, a cap, a welding helmet with the shade up, leather apron, and long sleeves. Oh, and the chips fly all over the place - I have to vacuum the shop afterward.) A table saw won't make _pretty_ cuts, but it will cut, and quickly.

-Mark


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## donmurray (Jan 21, 2009)

Here's an eBay item that has possibilities. 8 1/2" x 12" finned aluminum extrusion with 22 1" fins. $24 + $10 shipping.

eBay item #170297372305


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## ngrimm (Oct 19, 2007)

Has anyone tried cutting aluminum using a router with carbide bits? Seems like some hardwoods may be just as hard as aluminum.


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## Wirecutter (Jul 26, 2007)

This is how I'm going to do it:


















I didn't like the coldplate used by the Camosun/Circuit Cellar design - it appears to be made for a "2x2" layout of the IGBTs, rather than "inline 3", so I made my own. The slots for the pipe are milled with a ball end mill, as are the caps that cover the pipe trenches. It's glued together with Arctic Silver thermal epoxy. I milled the IGBT mounting surface smooth for maximum contact. What you see is the "test" fitting, so I haven't applied the thermal compound under the IGBTs just yet, but of course, I'll use the good stuff.

I also made brackets to support the driver boards. The white stuff that the board slot is cut out of is teflon that I had lying around. The water pump I'm going to use is from a Gen 2 VW Beetle. I'm going to make an arrangement for bench mounting for getting it running, and the final packaging is yet to be designed.

-Mark


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## DIYguy (Sep 18, 2008)

ngrimm said:


> Has anyone tried cutting aluminum using a router with carbide bits? Seems like some hardwoods may be just as hard as aluminum.


I have cut aluminum with carbide router bits before. It works ok. I sloted my CE plate mount holes with one come to think of it. The bits can grab so keep a good hold on the part and take thin cuts. Also, ur better off with an up-spriral than a straight cutter.

Cheers.


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## Bowser330 (Jun 15, 2008)

what about blasting the insides of the motor and controller with some cool air from compressed CO2 controlled by an automatic temp switch...


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## DIYguy (Sep 18, 2008)

Bowser330 said:


> what about blasting the insides of the motor and controller with some cool air from compressed CO2 controlled by an automatic temp switch...


Why would you want to do that? If forced air cooling isn't adequate... there are other issues. CO2 for cooling could be done a number of ways but I can't see the sense of it...sustainability would be an issue. Solid CO2 does sublimate but there are a number of unknowns here including what it would do to the commutator film.


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## Bowser330 (Jun 15, 2008)

Maybe for an emergency cooling situation only...that way you protect yout thousand dollar investments...


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## Tesseract (Sep 27, 2008)

Bowser330 said:


> Maybe for an emergency cooling situation only...that way you protect yout thousand dollar investments...


Why muck around with CO2 when you can go with the get-you-down-to 77K (-200C) extreme cooling power of liquid nitrogen for only a few dollars more?! 

Anyway, most controllers have a temperature sensor on or near the switches that will reduce the current limit (or at least shut down the controller) when they get too hot. Any controller *without* such protection was designed by an idiot and I wouldn't trust it to prop open a door, much less control an EV.


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