# Controller water cooling - Need some radiator ideas please.



## jtgreeson (Aug 14, 2009)

Here's what I have now:




















These are looking forward on the passengers side. Visible is the present 5 in square radiator and fan mounted low on aluminum angles. There is a empty area just aft of the axle.

Thanks for your ideas.


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## Vikingdad (May 22, 2011)

You might look into an aircraft radiator, they are much more compact and much more efficient, not to mention they are built like tanks! (don't want a failure up in the air!)

Look for aircraft scrapyards around your area. They cannot re-use the parts in aircraft like they do in cars so you should be able to get something for scrap value or less. I have a couple of coolers out of a Bell helicopter that I got for free, one is a "monster" at 8" high by 12" wide and 3.5" thick (6 rows I think) but has the same or better heat exchange as an automotive radiator many times larger. The other is much smaller, 12" wide by 3" tall by 2" thick. Both are labeled as oil to air coolers so they will be able to handle a water to air application just fine. I presume you are using water as your coolant? You might try adding some Red Line "Water Wetter" which increases the heat exchange efficiency of your cooling system (if only by a few degrees).


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## Vikingdad (May 22, 2011)

Why not plumb it up to the front of the car and use ram air instead of the fan? Or maybe have a thermostatically controlled fan in addition to the ram air? Not super familiar with the 914 but with your placement looks like it is highly turbulent airflow. Is there a place on the nose where you could open up a duct to a relocated cooler?


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## GizmoEV (Nov 28, 2009)

You might also contact Otmar. He has his own 914 that he uses to test Zillas. I'm sure he has figured out how to cool them in a 914. His evalbum page is http://www.evalbum.com/293


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## WSJ (Sep 18, 2008)

Have you considered using the transmission case to dissipate the heat? Synthetic transmission oil has a viscosity is similar to 10W30 motor oil. The synthetic transmission oil could be pumped through the Zilla and returned to the transmission, using the surface area of the transmission to dissipate a finite amount of heat in the air. There are many issues to consider with this approach, but if it provides enough cooling the advantage would be to eliminate the radiator and reservoir. All that would be needed is a small oil pump. 

I installed the Zilla with thermal compound to use the 3’ x 2’ aluminum plate as a heat sink. If a water cooling component fails, the aluminum plate will provide some back up cooling.
See my water cooled system pics 1 & 2.
http://public.fotki.com/WAYNEWANG/


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## Jimp (May 21, 2009)

Without knowing the temperature of the radiator, it is hard to narrow in on the answer. If the radiator temperature rise above ambient is not too severe you could increase the flow rate. The way that I think about this type of issue: optimize getting heat out of the heat source (controller) then add surface area of air flow to optimize getting the heat out of the radiator.


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## jtgreeson (Aug 14, 2009)

Vikingdad, good idea about the aircraft oil coolers. Plumbing to the front would be the best. The long lines would also help but would add to the expense and work. I would also have to cut into the front bumper. My small radiator has a fan that I control via a thermostat touching the controller base via a relay. I could add another fan to the additional radiator if required.

Wayne, thanks. My manual transmission already is getting hot being bolted to the hot motor. I have taken some heat measurements and the tranny's temp would not help cool the controller much.

Dave, thanks also. Otmar has been very gracious in the past answering my email questions. I'll contact him as a last resort due to respect for his time.

JimP, good info. I'll take some temp measurements of the radiator itself.

All good ideas. Thank you all very much.

Is anyone using a Zilla in 90 deg weather? What do you use for a cooling system?


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## Travdude (May 11, 2009)

At first, I was having some heat issues with the radiator and fans in the engine compartment. 
There was not enough air flow and the fans were annoying. There are some pics in my photo album. 

Now that I have mounted a transmission cooler underneath, everything is nice and cool, and no obnoxious fan.


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## WSJ (Sep 18, 2008)

I use a dual fan radiator core with 2 x 140mm fans and ½” hose, pump and reservoir, all ½”. The pump and fans run 100% of the time to provide maximum cooling. I have a temperature sensor mounted to the Zilla base plate, which runs at ambient plus 11° F.

Link to radiator and other cooling parts;
http://www.frozencpu.com/cat/l3/g30...g_Radiators-140mm_Dual-Page1.html?id=XJkiBsFD


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## jtgreeson (Aug 14, 2009)

Travis, thanks for the link to your album. I had not seen them before. You did a nice job on the '66 beetle. I like your installation of the cooling radiator. 

If you don't mine answering some questions: What's the dimensions of the radiator? Does it get any airflow through it as it sits horizontally below the motor? What amp and volt settings do you have on the hairball?

Thanks for you time in responding.


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## jtgreeson (Aug 14, 2009)

Wayne, Your 68 Beetle conversion looks great. Your 150 mile range is super. It looks like your computer radiator/cooler is about twice the size of mine (mine: 5 x 5 inches yours: 280 x 140 mm). 11 deg over ambient, good... Do you ever have any cooling problems? What max amp and volt limits do you have set on your hairball? Is your motor similar to the Warp9 in max power limits? 

This helps a lot, thanks.


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## Travdude (May 11, 2009)

JT, The transmission cooler is 11x18", it sticks out slightly below the pan and the fins are in line with the air flow. 

Zilla settings:
Max Amps - 640
Low Volts - 106
Low Volt Indicator - 112
Motor Amps F - 1000
Motor Amps R - 300
Max RPM - 5000

Your project is the cleanest 914 conversion I have seen, that thing must haul ass with all those batteries. Nice to see that I am not the only one still using Voltblochers! Let's see your Zilla settings..


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## jtgreeson (Aug 14, 2009)

Travis,

Ok, now it makes sense! Fins lined up with the airstream under the car. Excellent! Plus no fan. I think I'll steal your idea.

I just finished my last set of data collection/ test runs and here are my current settings:

Zilla settings:
Max Battery Amps - 900 (that's 5C)
Low Volts - 120
Low Volt Indicator - 145
Motor Amps F - 900
Motor Amps R - 0
Max RPM - 5500
Motor RPM error loging - 6000

Remember I have a 159 volt pack. At max speed and or max acceleration my pack volts never got below 124 volts with about 75% charge. I felt that 120 volts would be a good place to start cutting back the zilla. Also, I have the voltblochers turning on the "Valet" mode of the zilla when any cell drops below 2.4 volts. That happens anytime I use over 300 battery amps so I have a switch that defeats the protection circuit if I need the extra performance. Valet mode is 200 battery amps max and 400 motor amps max. Works good at protecting the batteries.

Thank you so much for your setup. It confirms a lot of my guessing.....


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## mizlplix (May 1, 2011)

It might be gross overkill but im building a 1930 Ford roadster with an AC50- 650 amp controller 120 volt pack Powerglide transmission. The transmission will be water cooled. The controller can be too. I live in AZ.....so the summers are brutal here. I have a brand new aluminum radiator from when it was ICE powered....with a powered fan....if I could figure out how to water cool the motor too I would not feel so bad about the huge radiator. BTW on these cars the radiator mounts the cowling so it is handy to keep it. I don't have to fill it completely too.


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## wb9hco (Nov 11, 2009)

I am not using it for the same purpose, but I am using a standard heater core for a cooler on my induction heater. Even if you have to buy them new, they are relatively cheap. 

The larger tubing size is more suitable to centrifugal pumps... don't need a lot of pressure drop in the small tubing of a transmission cooler core. 

One other note. Please do not use deionized or distilled water as cooling medium. Low ionic content water will try to dissolve any metallic components of your cooling system. A fella on one of the welding forums dissolved part of this tig torch using deionized water. No good deed goes unpunished...

A mixture of antifreeze suitable to your climate would be best, and I add a little water pump lube and anti-foaming agent in my cooling systems.

paul


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## ngcontrols (Nov 4, 2009)

jtgreeson said:


> Thanks for any wisdom you can share.


Several have contributed some good ideas. I just want to summarize a few things.

First, we've spent quite a bit of time optimizing a cooling system for these types of systems: 

http://www.ngcontrols.com/cooling.html

Here's the important factors:



The main goals are to have high fluid flow rate and a radiator that is good at getting rid of heat with a low temperature differential. Most of the points below are means to this end.
As large of tubing diameter as is practical. We went with 1/2". Toyota makes what seems like a nice inverter pump that uses 5/8" barbs. It would be great to go with this, but finding other components (e.g. radiator, controllers, etc.) that work with this diameter is a pain. The next generation WarP-Drive controller actually has a 1/2" chillplate so no reduction has to be made at all! We will soon be releasing a modified version of the current WarP-Drive that also uses this chillplate (I wonder if anyone will notice this little announcement?  ).
Keep pressure drops in all components to a minimum. For example, you want a radiator that boasts a minimal pressure drop for as high of flow rate as possible.
Change diameters as little as possible. Any time you increase or decrease diameters, there will be a pressure drop. Since your pump can only provide so much "head" (or pressure), every point where pressure is dropped will reduce flow rate. It's very similar to an electrical circuit - you have a fixed voltage from your voltage source, and every resistance will create a voltage drop for a given current flow.
Use as little tubing as possible, since every length creates additional pressure drop.
Someone made mention of not using deionized water. I'm not sure I understand this comment. Seems to reduce corrosion between any dissimilar metals, you'd want to have as pure of water as possible. For reference:

http://www.peakantifreeze.com/resources-faq.shtml

I try to make as lean of mixture of antifreeze to water as possible, since water has better heat transfer properties than antifreeze. Of course, you want to make sure the mixture is appropriate for your climate. You don't want the system freezing!

EV Source has put together some kits to adapt our cooling kit with the Zilla and Soliton:

http://www.evsource.com/tls_cooling.php (down a little ways on this page).

Hopefully those pieces of information help some.


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## GizmoEV (Nov 28, 2009)

ngcontrols said:


> Someone made mention of not using deionized water. I'm not sure I understand this comment. Seems to reduce corrosion between any dissimilar metals, you'd want to have as pure of water as possible.


You don't want to use pure deionized water because it will corrode the metals in the system. However, mixing it with antifreeze will eliminate the problem. I had a swimming pool I was setting up and took a sample of my well water into be tested. It was too "soft" and had to be "hardened" a bit to protect the pump. I'm now at a different house but it is fed with well water which is also quite soft. The brass fittings in the faucets and hose fittings to the toilet get eaten away by the water. They last several years but it isn't a great thing to have the hose to the toilet break, especially while you are away from home. 

Wow! What was that?!!??? Oh...a 1/2" chill plate announcement.


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## ngcontrols (Nov 4, 2009)

GizmoEV said:


> You don't want to use pure deionized water because it will corrode the metals in the system.


Ah, okay, I guess I didn't read that very good. I wouldn't even know where to buy deionized water 

I would just go with distilled water. Shouldn't have any problem with that.



GizmoEV said:


> Wow! What was that?!!??? Oh...a 1/2" chill plate announcement.


Pretty fun to play around with! Bumps up the continuous current rating quite a bit. Way out of the range of what a normal conversion requires though.


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## GizmoEV (Nov 28, 2009)

ngcontrols said:


> Ah, okay, I guess I didn't read that very good. I wouldn't even know where to buy deionized water
> 
> I would just go with distilled water. Shouldn't have any problem with that.


They are very similar and are available in the grocery store on the same shelf.

Regarding the chill plate...


> Pretty fun to play around with! Bumps up the continuous current rating quite a bit. Way out of the range of what a normal conversion requires though.


My understanding is that it isn't getting rid of the total amount of heat produced that is difficult but that it is usually produced in a small volume of material with minimal surface area to use to extract heat. This 1/2" plate then does a significantly better job of extracting the heat. I assume that this raises the continuous current rating by quite a bit. So in theory, if a similar thing was done with a Zilla its continuous current would also increase, right? If the cooling plate in the Zilla is only the size of the visible portion where the hoses hook up then 1/2" is significantly larger.

It is hard to tell from the photos how big the current chill plate is in the WarP-Drive. Maybe the one the local community college ordered will be her by our June EV meeting and I'll finally get to touch one.


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## WSJ (Sep 18, 2008)

jtgreeson said:


> Wayne, Your 68 Beetle conversion looks great. Your 150 mile range is super. It looks like your computer radiator/cooler is about twice the size of mine (mine: 5 x 5 inches yours: 280 x 140 mm). 11 deg over ambient, good... Do you ever have any cooling problems? What max amp and volt limits do you have set on your hairball? Is your motor similar to the Warp9 in max power limits?
> 
> This helps a lot, thanks.


The 150 mile range was calculated form measured battery current 25A at 25 MPH and the specified discharge time form the battery specifications at 77° F. I have never seen the over temp light on. If I didn’t have the 3’x2’x1/8” aluminum mounting plate to mount the Zilla on with thermal compound, I would mount it to a heat sink with fans for backup cooling. Semiconductor MTBF is reduced by 50% for every 10° C increase.
The GE motor is similar to the Warp9 in max power limits. My motor fan is a 53 CFM, 120 VAC, 400 Hz, 20,000 RPM Vaneaxial Aircraft Fan. It also doubles as an audible warning device.

Zilla settings:
Max Bat Amps - 400
Low Volts - 115
Low Volt Indicator - 121
Motor Amps F - 500
Motor Amps R - 500


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## wb9hco (Nov 11, 2009)

Leaving the piping and pumping side of the discussion aside for the moment, I would point out the WIKI entry:
http://en.wikipedia.org/wiki/Purified_water
note the section:
****************************
Non-laboratory uses*

Distilled or deionized water is commonly used to top up lead-acid batteries used in cars and trucks and for other applications. The presence of foreign ions commonly found in tap water will drastically shorten the lifespan of a lead-acid battery.
Distilled or deionized water is preferable to tap water for use in automotive cooling systems.[7] The minerals and ions typically found in tap water can be corrosive to internal engine components and can cause a more rapid depletion of the anti-corrosion additives found in most antifreeze formulations.[8][9] Distilled or deionized water is especially important in automotive hybrid system component cooling systems, mixed with hybrid system coolant, to prevent corrosion or electrolysis of hybrid components.[10]
*****************************

I don't believe that the inclusion of antifreeze in the automotive cooling section is emphasized enough.

The use of high resistivity water in a battery or a cooling system is to remove contaminants, there will be plenty of ions to satisfy the waters' need for solutes in a battery. In a cooloing system you must provide them.

A number of years ago i was involved with the construction of a pilot analog chip fab plant. Part of the installation was a deionized water system. It used water softeners feeding a RO system which then fed a cation and anion system.
This resulted in 18 megohm water... When we started detecting trace hydrocarbons on the wafers the original thought was that we had somehow been subjected to a biological contaminant. What we later discovered was that the H/C were coming from the PVC piping system. The water was dissolving the pipe and fittings. The high purity piping now used in the industry is "KYNAR' which can only be threaded, clamped or heat fused.


18 megohm water will dissolve ANYTHING, just that certain materials are 'eaten' much slower than others. Raising the temperature accelerates the process.

While it is true that 18 meg water would not by itself allow electrolysis, as the water would not technically be an electrolyte, it soon will be. It will first absorb any metal, and once the solution becomes conductive, the electrolysis will be come the predominant chemical reaction in the system.

The only reason to use deionized or distilled water in a cooling system is to control what the contaminants are introduced. In the case of a cooling system the contaminant will be antifreeze. Modern antifreeze products also contain corrosion inhibitors and buffers to allow the coolant solution to exist in a multi metal system. If you don't add something the water will take care of it all by it's self.

paul


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## jtgreeson (Aug 14, 2009)

Wayne, Paul thanks for the info. Ngcontrols, thanks for sharing your knowledge. 

Here's what I ended up doing:

































I ended up just buying a transmission cooler radiator at Advance Auto, made some brackets and mounted it near the rear bumper. I figured it should get some airflow over it. I just got back from testing it. The Zilla stays below 55 deg C up to 75mph highway speeds. A big improvement. Before I got the overheat light if I stayed at 50 for any length of time. This is at 90 deg outside temperature. The over heat now occurs above 85mph. The Zilla temp shoots up to 65 deg or so then starts cutting back on the Motor amps, as it should.

As NGcontrols said, it must be a flow issue. My tubing is 3/8 in ID and problably 12 ft of hose total. I'm happy with the results - a year round capability of 70 mph here in FL. I'll just have to wait for cooler weather to break my 107mph personnel record....... as if I need to.

Seriously, thanks everyone for your comments and help.


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## WSJ (Sep 18, 2008)

Thermal fatigue is a ware-out type of failure that occurs in silicon power devices as a result of the thermal cycling produced by changes in power dissipation and heat sink temperature. When a semiconductor is alternately heated and cooled, cyclic mechanical stresses are produced within the device due to differences in the thermal expansion of the silicon and the metallic material to which the silicon is attached. The magnitude of the cyclic temperature, a power semiconductor encounters, is directly proportional to the stresses that lead to fatigue failures. Reducing the cyclic thermal stress increases the Mean Time Between Failures (MTBF). High power motor controllers experience very severe thermal cycling stress, therefore, the cooling requirements are very important to maximize the MTBF.

The cooling system design will directly affect the controller life. The additional cost of a robust cooling system is relatively low compared to the cost of a controller failure.

It would be interesting to post the Zilla base plate temperature rise above ambient for various cooling systems. My temperature sensor is mounted to the base plate at the upper right mounting hole.

Six channel scanning thermometer.


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## GizmoEV (Nov 28, 2009)

Wayne,

Where did you get that scanning thermometer? I did a google search and didn't find anything like it.


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## WSJ (Sep 18, 2008)

GizmoEV said:


> Wayne,
> 
> Where did you get that scanning thermometer? I did a google search and didn't find anything like it.


I saw one on eBay a while ago, but nothing up for bid today.
http://www.analog.com/static/imported-files/data_sheets_obsolete/658792335AD2037.pdf

http://www.seekic.com/forum/22_circ...digital_thermometer_with_printer_output_.html

This one is big $
http://www.thermoworks.com/products/logger/digisense_12ch_bench.html


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## antonp (Jun 9, 2011)

you could also try plumbing the controller cooling in with the heater core for cabin heating during cooler temperatures. with a fluid pump to move the coolant around the system.


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