ESC Cooling Concept- Theory and Practice

[questtek]

Pictures? How much is the temp.difference?

The picture shows the inlet temp on the right and the cooled temp after passing thru the coils on the right. ambient air temp was about 74 degrees F

[questtek]

[QUOTE=Ken Haines;131750]You guys are doing great on this cooling R&D. I do not have anything to add, just wanted to let you know that I'm following this closely. My free time to field test this stuff may not be soon enough as you guys have really jumped all over this.
Maybe I can pledge that whatever is the best end result, I will race test at the 2010 FE Nats.
Keep up the great work!!!
Thanks, Ken [/QUOTE


Thanks a bunch, that would be great. When I get closer to developing a much more refined coolong unit, backed with lots of test data, I will send a system for you to expertment with. If you have a newer V-3 Eaggle Tree I can send it along with three temp probes. This will allow you to measure inlet water temp, post cooling water temp and actual ESC temp.

[MarkF]

This is great stuff. I have burned up more speed controlls at SAW events than I care to admit. What about using a small piece of dry ice so the cooling effect last longer. We had a guy who use to race with us a long time ago who made a little wood box to put his controller in and then he put a small piece of dry ice in the box with it. It worked great untill the dry ice melted and got condensation in the controller.

Mark

[Ken Haines]

[/QUOTE


Thanks a bunch, that would be great. When I get closer to developing a much more refined cooling unit, backed with lots of test data, I will send a system for you to experiment with. If you have a newer V-3 Eagle Tree I can send it along with three temp probes. This will allow you to measure inlet water temp, post cooling water temp and actual ESC temp.

Yes I do have Eagle Tree Systems, 1Pro, 1 Standard. the Rev I do not know. They are the older big data loggers with the remote readers, there is plenty of room in both boats that I'm considering. The class at nats that this most applies to is LSO. Hopefully they will still be running it as a 4 minute timed event. This is where the heat came into play at the 2009 nats, LSH would also be a consideration to maintain a very aggressive set-up by better cooling.
Thanks, Ken

[Jeff Wohlt]

Just tested my little ice pack (see below) I used a coke bottle full of 90 degree water but gravity feed...no pump. Water flow seemed about what the rudder would do on my boats...slow steady stream

Water was 75 degrees coming out. I measure it using my digital meat thermo. Pretty accurate for what it is. Actually you will probably be slowing flow as it goes around everything which is even better.

So now I wonder what a couple more tubes will do and using copper tubing...which I did not have.

BUT...the good news is it does drop water temps considerable for only 15" of brass being in the ice.

I would like to pump more thru it and see how long it lasts.

[properchopper]

Joe, this is great info and I commend you for addressing this issue, one which is of considerable importance to FE. One concept which has been previously discussed, without complete consensus, is the flow rate between the cooling medium and the heat source [e.g. motor and/or speed control]. I'm sure you'll agree that the thermal transfer rate, or cooldown effect, is intimately related to this factor. I'd like to hear your take on this variable. Thanks for your efforts & keep us posted

[Jeff Wohlt]

hmmm...just added 3' of silcone to the exit and same test...now water is 70 degrees coming out of tube. Slowing flow is the key. 5 degree drop.

so about 20 degree drop in water temps...

My goal is to create temps from running in summer time....I doubt any of us need cooling when the water temps are 60 degrees anyway. 90 degrees is probably more than needed.

Going to try 75 degree water now.

[Jeff Wohlt]

Interesting....74 degree water only came down to 70 degrees.

So hotter water is cooled much better.

[Jeff Wohlt]

So obviously Joe has more tube in the ice and using copper. His temps went down more. Mine has little in it and was actually surprising how well it did for so little and easy to make. to drop 20 dergrees is pretty good.

Yes, pulling heat from the ESC is the key...it has to have good contact with fets. I think plates should have more than 2 outlets on a plate on each side when we need to cool all rows of fets...another reason the Pletier could be excellent...full contact on fets.

Maybe the Peltier is key or the water circ method but I worry about more motor interference from anything powered. Peltier might be better as there is not spinning motor. Then water cool the top heating part of it. But doe this take away from the cooling side?

They pull a bunch of power is the problem. A small 3S pack should be able to pull 5-6 amps to keep it running. I know it will drain a deep cycle battery over a few hours. I have done it with my cooler.

[questtek]

Miniature pump information…

Years ago I bought a bunch of small 12 vdc pumps at surplus. I used most of them for the “blood injection system” for the remote control great white shark fins that I built. Going thru my spare hardware I did run across two of the pumps that remain. I will provide you with some details so you can consider what may be available if in your cooling situation you opt to go with adding an additional pump to improve ESC and motor cooling.

I have included pictures of the two miniature pumps. One I covered in black shrink tubing, the other is the bare case. The pumps were made by Oken Seiko Co. Ltd, Tokoyo and designed as a rolling pump. (This type of pump no impellor but a unique settle of wobble diaphragms to push the water). If it would do you any good, the Model Type of the pump is P0532197Ce27-3379851-Rev 1 (Good Luck!)

The pump specs are as follows:
Size: 2 1/4 “ long x 1” dia.
Weight 2.1 oz or 60 grams
Power required is 12 vdc and draws a max of 200 mA when pumping water
Pumping rate as I just tested them was 12 oz of water per minute.

So, for a 4 minute run, as many members have discussed, the total volume of water used if the system is open loop (water pumps out) is 48 oz. Since there are 128 oz per gal and water weighs 8.34 lbs/gal this means the weight of water to provide 4 minutes of continuous cooling with this pump would be 3.12 lbs or 1419 grams of water. This does not seem practical to me which why we need coolant materials that have a much higher heat transfer than just water.

You could control this pump by a spare remote switch on your transmitter.

Remember, the rate of heat transfer from your ESC is a function of the thermal coef of the conduction material, temperature difference AND flow rate of the cooling liquid to remove the heat. Keeping this flow rate high is imparative

Ideas, suggestions, comments?

[D. Newland]

Joe-great work on this!

Where are you in Ca?

[questtek]

Blue Ice - It has been discussed by others in this forum so now it's time for a bit of detail on this magic blue gel.

This blue gel substance, normally called Blue Ice, is a re-freezable ice substitute. It is currently marketed by RubberMaid and a few other vendors. It needs at least 3 hours to completely freeze.

I just picked up two differnt pack of Blue Ice, a small hard plastic container and a soft plastic bag. You can see them in the attached pic relative to my hand.

The Blue Ice in the hard plastic container is 2.8”x1.3”x4.9” and weighs 6.2 ox or176 grams. It costs 94 cents and is found in the sporting good section of WalMart. The soft patic bag of Blue Ice is the same price.

The Blue Ice mystery liquid seems to be a trademark secret as far as I can tell. I could not even find an MSDS safety sheet for the product. I was just curious. I really do not know what is in it JUST how well does it work! To find this out I filled two of my first generation 25 cent tupperware containers with Blue Ice from the soft plastic pac and put them in the freezer. There was more than enough to fill both test cooling tanks with their internal coils of copper tubing.

Tomorrow I will continue testing but tonigt it's Blue Ice chill time.

The upside of this project is how little money needed to experiment. I probably have less than $10 invested and that includes 4 tupperware containers, 1/4" dia copper tubing, gromets and even the magic Blue Ice mystery fluid! That's less that the postage to have another ESC delivered! But, add the three Eagle Tree data Loggers, 12 thermocouples probes and other sensors, large LCD data display monitors, tablet computers.................Opps, my wife is coming in!

[questtek]

Joe-great work on this!

Where are you in Ca?

Thanks, this is a practical and fun project. I keep a bag of burnt our ESC's on my desk for motivation!

I live in Lake Forest, Ca....near Newport Beach - about half way between LA and SD. I am vey fortunate that I actually live on a man made lake which is absolutely perfect for FE experimenting. No driving, just walk 20 feet from my workshop to the dock. Even have a 16 foot electric boat as a recovery vessel.... (and cocktail cruising. I welcome anyone in the area to stop by.....and have include a few pics in case anyone takes me up on it!

[Jeff Wohlt]

I like those pumps. I have found some close to that but am looking for cheap.

I still think a pump with closed loop back into the tank is going to be faster cooling but more headache to build.

I was going to slit the jell hard pack and put the coil in it but wanted to try some tubes thru it first. It does work as it came from 90 to 75...so if you can keep that water in more tube you certainly should be cooling.

Good stuff

[questtek]

I like those pumps. I have found some close to that but am looking for cheap.

I still think a pump with closed loop back into the tank is going to be faster cooling but more headache to build.

I was going to slit the jell hard pack and put the coil in it but wanted to try some tubes thru it first. It does work as it came from 90 to 75...so if you can keep that water in more tube you certainly should be cooling.

Good stuff

Jeff, The surplus pump I showed was only a few dollars each. They or something similiar should be out there for low cost.

Great work with the Blue Ice gel pac. I will use my Eagle Tree set up to test the units I made up with the copper coil from cooling. I will use one the pumps I have but calibrate the flow rate and see how it changes the temp. At 12 VDc the output is 12 oz per minute but at 6 or 9 volts I a sure it will be considerably less. I am anxious to hear your results.

I am not quite convinced yet the use of an additional pump is necessary. The amount of flow even from a rudder intake is quite large when the boat is moving at a reasonable speed. Only testing will tell!