# Controller Cold Plate



## grayballs (Aug 27, 2008)

Most of the controller failures, I've witnessed, have had to do with heat. In our application, we have a space issue (imagine that!) with two controllers, two motors, etc. The decision was to build a liquid cooled, sandwiched cold plate.









This is the first attempt

















The tags indicate where the taps for coolant are going. The plan is to thru-drill and tap so that, depending on conditions, we can inlet or outlet, top or bottom either side.


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## etischer (Jun 16, 2008)

to help with sealing, you may instead consider press fitting a copper pipe in the aluminum. this is how my cold plate was made. 

Some cold plates even have the copper tubing press fit into the aluminum plate, and mate the parts directly in contact with the copper tubing. 

You might try to find something off the shelf that will work, it might be cheaper (although less fun and not as cool). I'm using a cold plate from mcmaster, it cools my 90hp inverter just fine.


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## grayballs (Aug 27, 2008)

The plate, center picture, left, shows o-ring grooves around each penetration. I'm measuring .015 press, and using allen head caps for assembly. The crosss drilled connections are waiting for a tool to cut the threads for an o-ringed hi-pressure fitting. After a pressure test I can decide whether to refrigerate the plate (dx) or just circulate refrigerated coolant.
I'm considering sealing off all air flow through the car, no radiator openings, adding a belly pan, etc. ('been lurking on the ecomodder site) so standard, finned heat sinks are less than desirable. Next up are the motor mounts,, we have liquid cooled cases/mounts in the works, then on to the battery cases. The idea is to try to keep everything near 55 DEGF, no matter the outside conditions. I'll post more pictures as things move forward,,, or?


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## grayballs (Aug 27, 2008)

'Just a quick follow up, for the PM's I received. This shows the plates with o-rings and ready to pressure test.










Final assembly. fittings installed and ready to mount in the car. Only the decision about whether to refrigerate directly or to circulate chilled water remains. The assembly will tolerate either. The fittings are located to allow top, bottom or either side for the connections. Now,,,, the motor mounts.


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## etischer (Jun 16, 2008)

I approve 

That looks like it should work well. Nice job machining the o-ring grooves. The nice thing about having the controller watercooled is you can mount the controller in the trunk where it is well protected, since it does not require air flow for cooling.


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## grayballs (Aug 27, 2008)

Thanks for the kind words,,, 
I bought that mill for my retirement gift, to myself. Now all I have to do, is learn how to run it.


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## dimitri (May 16, 2008)

What water pump will you be using with this setup?


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## grayballs (Aug 27, 2008)

dimitri said:


> What water pump will you be using with this setup?


There has been no decision, yet on the water pump issue,,,, we're considering using a DX system (small ac unit?), with the idea of recovering the heat for the cabin. This would give us a lot more control over temps in various areas (motors, battery box, cabin, etc.) and (maybe more importantly) air flow through and around the car. Danfoss builds a couple of nice small BLDC compressor units, that just might do the trick. So far, we are just building and testing parts.


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## etischer (Jun 16, 2008)

grayballs said:


> There has been no decision, yet on the water pump issue,,,, we're considering using a DX system (small ac unit?), with the idea of recovering the heat for the cabin. This would give us a lot more control over temps in various areas (motors, battery box, cabin, etc.) and (maybe more importantly) air flow through and around the car. Danfoss builds a couple of nice small BLDC compressor units, that just might do the trick. So far, we are just building and testing parts.


just be aware of condensation if you go with a refrigerated cooling system.


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## grayballs (Aug 27, 2008)

etischer said:


> just be aware of condensation if you go with a refrigerated cooling system.


30+ years as a fitter with a refrigeration ticket had led me to consider the condensation idea. My thoughts are to try to keep things in the 55 - 60 DegF area. Even in our coastal climate, that should avoid the moisture issue. (with minor adjustment).
After lurking here for so long, I'm convinced that the reliability of these systems can be greatly enhanced with some simple temp control. At least, I'm convinced that it's worth looking at,,,, and,,,, I get to play with new toys in the name of research. (now, convincing my wife that's what I'm doing?)


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## JRP3 (Mar 7, 2008)

Very cool  I'll be interested to see how this turns out.


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## Tesseract (Sep 27, 2008)

My suggestion for an inexpensive 12V water pump that can (probably) run continuously: a bilge pump. Note that they often use 3/4" barbed hose fittings, which may be a bit bigger that ideal for this application.


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## JRP3 (Mar 7, 2008)

I don't know about that, most bilge pumps are made to sit in a sump and are made for intermittent use. If your bilge pump is running continuously, you have a problem  You really only need a low pressure low volume circulator pump, maybe something like this, though it may not be good for continuous use. http://www.adventurerv.net/shurflo-nautilus-single-station-water-pump-gpm-p-1713.html


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## Tesseract (Sep 27, 2008)

JRP3 said:


> I don't know about that, most bilge pumps are made to sit in a sump and are made for intermittent use...l


I don't know, either, but I would expect a bilge pump to be rated for much longer run times than a faucet pump for an RV?!?!

And while it is true that if your bilge pump is running continuously you have a problem, that is when you need a bilge pump the most, right?

They are designed for high volume at low pressure, which is ideal for this application.

That they have to sit in a sump is no big deal - you want a tank somewhere in the loop to get rid of the air bubbles. A 3.5gal. bucket with lid from the Home Despot, Blowes, etc. would work well here (might not look pretty, but it would work).

My $0.02


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## aeroscott (Jan 5, 2008)

check out your pick and pull Mercedes and BMW run a small electric pump to enhance the heater out put . 2to3 gpm after 1994 they are magnetically coupled , no seals . New they cost 150.00 at pick and pull under 20 .


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## JRP3 (Mar 7, 2008)

Tesseract said:


> I don't know, either, but I would expect a bilge pump to be rated for much longer run times than a faucet pump for an RV?!?!


Presumably the faucet pump is expected to last through daily use for the life of the RV. The bilge pump will only see occasional intermittent use, unless there is a real emergency, but that emergency will be short lived as well. I honestly don't know which would last longer in an EV.


> They are designed for high volume at low pressure, which is ideal for this application.


Does this situation really call for high volume?


> That they have to sit in a sump is no big deal - you want a tank somewhere in the loop to get rid of the air bubbles. A 3.5gal. bucket with lid from the Home Despot, Blowes, etc. would work well here (might not look pretty, but it would work).


Seems very inelegant to me, I see more of a closed system with the fill at a high point to bleed off air. My take on it anyway.


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## steiner (Dec 8, 2008)

aeroscott,

The pumps that you are talking about for the BMW/Mercedes, are they mounted in the engine bay or up under the dash?

Thanks...
Rick


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## aeroscott (Jan 5, 2008)

in the engine bay . look for heater hoses . they pack these things into tight spaces .


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## aeroscott (Jan 5, 2008)

on the MB there is a solenoid water control valve ( separate unit ) with rubber diaphragm that fails , 4 small screws on top of this will help to id , pull the screws extract the piston to expose the rubber bellows /diaphragm , check for tears if you need this valve . kits are available for this . if bellows is bad it will not leak externally but will internally.


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## Wirecutter (Jul 26, 2007)

The water pump for my cold plate arrangement is an electric water pump for a VW Beetle.


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## aeroscott (Jan 5, 2008)

the bulge pumps will run a very long time . I get years out of them , running 15 min to 1 hour or longer . I still prefer the MB or BMW pumps , but 1 hour or more a day should be OK . PS I didn't know VW used these pumps too.


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## engineer_Bill (Jun 24, 2008)

grayballs said:


> There has been no decision, yet on the water pump issue,,,, we're considering using a DX system (small ac unit?), with the idea of recovering the heat for the cabin. This would give us a lot more control over temps in various areas (motors, battery box, cabin, etc.) and (maybe more importantly) air flow through and around the car. Danfoss builds a couple of nice small BLDC compressor units, that just might do the trick. So far, we are just building and testing parts.


What kind of compressor? where do you get them. Would a compressor run the evaporator condesor of the cars A/C?


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## grayballs (Aug 27, 2008)

Try this,,, they are small compressors, designed for DC refrigerators. I think they would be on the small side for auto AC but that would depend on your application.

http://www.rparts.com/Catalog/Major_Components/compressors/Danfoss/danfoss.asp


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## grayballs (Aug 27, 2008)

'Found this in the Wiki,,, might also have something you can use




http://www.revoltcustomelectric.com/components-accessories.html


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## johnnyfoos (Sep 1, 2008)

A good long life pump, 12 VDC,
Can be found used in the liquid cooling of computers
$0.02


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## JRP3 (Mar 7, 2008)

The few I've seen aren't exactly cheap for what they do.


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## johnnyfoos (Sep 1, 2008)

No, not cheap.
But, you get what you pay for!
100,000 life hour Vs maybe a couple hundred for a bilge pump.
I'm sure one of the $80 pumps would last longer than than the controller,
I've been running one in my computer for about 4 1/2 years now
On more than off
just my
$0.02


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## JRP3 (Mar 7, 2008)

johnnyfoos said:


> But, you get what you pay for!


Sometimes. Sometimes you get less though. 
I'm sure they are durable I just wonder if they have enough volume to cool a controller, which has way more heat to dissipate than a CPU.


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## dimitri (May 16, 2008)

I was aware of CPU liquid cooling systems, but never actually used one or seen one up close. After reading this thread I actually looked one up, here os the link
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=10006294

This sure beats my current setup, its a few bucks cheaper than I spent on automotive water pump from one of German cars, but most importantly, the size of fittings on this pump is better match to my controller. I had to buy a bunch of bronze fittings to step down from 3/4 inch automotive size hose to 1/8 NPT on the controller. All those fittings cost me about $30  alone.

As for volume , this one is rated 500L/h , which is above 2 GPM, which is plenty for automotive controller.

Controller doesn't produce that much heat actually, but it produces it in a small concentrated spot at the power module, so as long as you have a liquid circulating thru that spot, controller is happy.

If I was to build my next water cooling loop for the controller, I would definitely buy this CPU pump.

Thanks for the tip....


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## JRP3 (Mar 7, 2008)

Good find, that's about half the price of what I was coming up with. As for the amount of heat produced by a controller I guess it depends on the power it's producing and the efficiency. A 144 volt controller pulling 400 amps at 95% efficiency will have about 2880 watts of waste heat if I figured right, which seems like way more than any CPU would see. 2 GPM does sound like enough, but it also depends on how quickly the heated fluid dissipates that heat. 2 GPM of fluid that's still hot might not work that well. I'm sure there is some formula to figure all this out that I don't know. Flow rate, fluid heat transfer efficiency, surface area required, etc.


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## grayballs (Aug 27, 2008)

dimitri said:


> I had to buy a bunch of bronze fittings to step down from 3/4 inch automotive size hose to 1/8 NPT on the controller. All those fittings cost me about $30  alone.
> 
> As for volume , this one is rated 500L/h , which is above 2 GPM, which is plenty for automotive controller....


I installed 1/4" Hyd. fittings on this plate for just that reason. If I decide against direct refrigeration, I wanted to make sure there was enough flow.


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## dimitri (May 16, 2008)

JRP3 said:


> Good find, that's about half the price of what I was coming up with. As for the amount of heat produced by a controller I guess it depends on the power it's producing and the efficiency. A 144 volt controller pulling 400 amps at 95% efficiency will have about 2880 watts of waste heat if I figured right, which seems like way more than any CPU would see. 2 GPM does sound like enough, but it also depends on how quickly the heated fluid dissipates that heat. 2 GPM of fluid that's still hot might not work that well. I'm sure there is some formula to figure all this out that I don't know. Flow rate, fluid heat transfer efficiency, surface area required, etc.


Right, so it all depends on your choice of heat exchanger, a.k.a. radiator. In my case, I routed water thru my heater core, which serves as a radiator and provides with some cabin heat on "cold" Tampa winter mornings 
Of course up North you'd need your heater core for more serious heat, so you'd have to either keep OEM radiator ( too big for the job ) or install a smaller radiator for controller cooling. I actually bought small ATV radiator on Ebay for this reason, but eneded up using heater core instead. ATV radiator seems perfect for the job, it has builtin tank with the cap and its small enough to fit in tight places. It was $35....


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## JRP3 (Mar 7, 2008)

I suppose you could also buy another heater core which might be even smaller than the ATV radiator. Another parameter to consider, what resistance would the system have and does the computer pump have enough pressure to push the fluid through the system? I would think a CPU cooler is a pretty small system with little need for pressure.


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## johnnyfoos (Sep 1, 2008)

"how quickly the heated fluid dissipates that heat."
1977 Pontiac Bonneville with A/C Heater core
A very good core highly rated by the liquid cooling types
I have two in my system, way over kill but room temp is what I wanted.
With good plumbing you could have heat in the cold season and not in the warm season,
using two also.
0.02


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## grayballs (Aug 27, 2008)

I remember an old truck, that I had 'back when', that ran the heater fan near continuous,,, when the cabin needed heat, it vented to the cabin,,, when it didn't, it vented outside....... simple manual controlled damper solution.

By the way,,, for the 2 or 3 of you that PM'd, in the beginning of this thread,,, I did run 2-3 extra, if you're still interested


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## johnnyfoos (Sep 1, 2008)

After looking over the pictures of your cold plates again,
You could drill small holes all along the liquid path, just a 1/16 or less
deep. To get the liquid to kind of tumble or swirl around, not just passing
through. This is proven better cooling.
Just check out the water blocks used in cpu or video card liquid cooling.
Yours could be much better just drilling some swirl pot holes.
Again, just my 
$0.02
And your work is very GREAT!!
I'm way behind all the people here but some day ,maybe


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## grayballs (Aug 27, 2008)

johnnyfoos said:


> You could drill small holes all along the liquid path, just a 1/16 or less deep. To get the liquid to kind of tumble or swirl around, not just passing through. This is proven better cooling.


 
The later unit has shallow internal fins,, like a finned heatsink, just inside out. It was made for a larger single controller and for liquid cooling. Each new project brings something new to the table. I try to build what the customer wants.


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