[timthefinn]

Natural circulation (no pump) is tough to establish and maintain. You need a large height difference between the heat sink (oil cooler) and the heat source (the controller) and the heat sink needs to be higher. You'd need to mount the cooler on your roof. Even if you can get that height differential, you need some an upward slope directly from the heat source and a downward slope directly from the heat sink to get it started and that is difficult in a calm system. Driving around makes it more difficult. Also, even if you do get natural circulation, the temperature difference between the source and sink tend to be high which means your controller will maintain a much higher temperature than if it was forced convection.

I'd put a small pump in the path and put a temperature sensor that only turns on the pump when the controller gets too warm under high load. Water cooling will be far more effective than air cooling. I'd be concerned that the controller would overheat powering that land rover around with just air cooling.

 

[arklan]

my water pump cost 6 bucks off ebay and uses less power than my contactor

 

[goingbush]

Thanks guys , Chill Plate with pump it is then .
I'll post pics as I make it (next week)

arklan , you have a link to that pump by chance ??

 

[arklan]

https://www.ebay.com/itm/Ultra-quie...Pump-New-MA-/162745268304?hash=item25e45fb850

connects to radiator and zilla

 

[goingbush]

Chill plate done. Ducts are 18mm wide x 10mm deep. 1/2" x 1/4 NPT barbs .

I decided on a small VW automotive pump , one of these
https://www.aliexpress.com/item/2Pin...818270209.html

any tips on how to bleed, I imagine its going to have some air pockets.

 

[timthefinn]

Generally have the pump at the low point of the circuit and the expansion tank off a T at the high point. I'd sequence it as pump, controller, T to expansion tank, cooler, then pump as long as the cooler is installed so the loops go side to side, it should get water to the pump and then the pump should sweep most all the bubbles out and carry them to the T and the expansion tank.

You could try vacuum filling (pulling a vacuum on it and then letting water enter), but that is only somewhat effective, especially when hoses collapse and prevent air migrating to the vacuum pump.

Nice looking chill plate, BTW.

 

[Duncan]

As far as removing the air is concerned my batteries were a big problem with that I just flushed them with a garden hose while they were on end so that I got shot of the air

On the complete system you need to have a way for the air to collect in your expansion tank - I used an old power steering pump fluid reservoir - you won't need a pressurised system as you don't want high temperatures

 

[arklan]

i think people are over thinking this, just put ur pump lower than the top of the radiator, fill it with water and let it go.
sure there will be some air in the top of the radiator but so what?
its not under pressure and the pump will always be in water.
just make sure ur chill plate is lower than the top of ur radiator aswell.

 

[GoElectric]

The best solution is an air-trap/separator: a small plastic tank with air/water coming in one side and water going out the other. Just fill the tank and turn on the pump. as it sucks fluid out, air/water will come in the other side and the air will magically separate from the water!! add more water though the top until the system is full and the return line is running pure water. Then just put on the cap!

You might have to prime the pump, so put the separator above and that should do it.

Not so easy to find a tank which has the holes in the right places, but I had some made, and could send you one.

I should have a pic somewhere if you are struggling to get this.

 

[GoElectric]

I'm going with air-cooled, but sort-of in a different climate....

 

[Moltenmetal]

By my calcs, the controller (1238) dissipates only about 250 W. Not worth the bother of water cooling. I have a muffin fan mounted to the back of my heatsink, with the heatsink mounted in the wrong orientation (i.e. controller face up and horizontal, so the fins of the heatsink are pointed downward) and never have problems with controller temperature. It gets hot enough here in the summer.

 

[GoElectric]

Exactly what we were thinking of doing.

 

[goingbush]

<snip>

Not so easy to find a tank which has the holes in the right places, but I had some made, and could send you one.

I should have a pic somewhere if you are struggling to get this.

All good, thanks for the offer , I found a good looking expansion tank, should do the job.

 

[goingbush]

By my calcs, the controller (1238) dissipates only about 250 W. Not worth the bother of water cooling. I have a muffin fan mounted to the back of my heatsink, with the heatsink mounted in the wrong orientation (i.e. controller face up and horizontal, so the fins of the heatsink are pointed downward) and never have problems with controller temperature. It gets hot enough here in the summer.

Oh well , I do have an extruded finned heatsink but now that Ive made the chill plate I might as well use it.

Just thinking, if the liquid cooled plates are not necessary why do HPEVS sell them - oh hang on they also sell mounting plates to bolt the Controller on top of the motor - that would be more like a hot-plate !!

 

[piotrsko]

Fwiw: it isn't how much heat you can remove, it is how fast you can remove it. The dies on most power electronics are measured in square inches. A 250 watt soldering iron gets much hotter than a laptop.

 

[itchyback]

Hey, Can you tell me more about your chill plate.

Im really wondering about why you did so few turns with such a wide track. how does that compare to a narrower track with more back and forth tracks?

 

[goingbush]

Sorry Itchy , now your getting into the theory of thermodynamics, way above my pay grade .

I just looked at an existing designs and plagurised , Aluminium is a great medium for conducting away heat, I figuired the thicker walls between the channels would soon carry heat away to be removed by the liquid.


http://www.hpevs.com/hpevs-chill-plates-for-cooling-curtis-instruments-for-ac-controllers.htm

 

[itchyback]

A man after my own heart, but really, theory of thermodynamics cant be that hard can it?!

 

[Duncan]

High itchy
I am an engineer and I can do the thermodynamics but as Molten says there is not very much energy to dissipate
My plate has two long drilled holes and a single cross hole
I'm using a solar water pump - little thing draws less than an amp and is almost completely silent
And an old power steering pump reservoir as the reservoir/air separator

The highest temperature I have seen so far is 30C

The most important thing is to get a good thermal connection between your plate and your controller