# Best location for cooling fans on a Curtis 1231C?



## dynoguy (Jun 29, 2010)

Which begs my 'I am such a newbie' question, 'How important are cooling fans and a heat sink?'


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## Guest (May 7, 2011)

Very Very Very Very important. It is also important that the surface of the sink be flat and that you use proper heat sink thermal compound. Not too much but enough to cover the base and provide a clean transfer from controller to sink. Put the fan on the fin side and direct the flow onto the fins. Most controllers don't have a sink when you buy it because each setup is custom. So mounting is your job and it's your job to do it right. A big flat piece of aluminum is not enough. It must be a good sink and fan.

Do not skimp on this issue. Your controller generates lots of heat and needs a good way to get rid of that heat. 

Pete


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## Guest (May 7, 2011)

Mount the heat sink directly to the controller. Do not mount to the plate then the sink. Mount that sink directly to the controller. Leave plenty of space for air flow with the fan. The fan in the photo gives plenty of air flow. Once installed that controller never overheated. Never even got hot enough to prevent touching. It did the job intended. It is a must. Your setup begs for overheating. Even with proper thermal compound it will cause a decrease in heat transfer. 

Be sure the parts are flat and that you use proper thermal compound. No exceptions. Many mount with crappy heat sinks and usually on just a flat plate. It is not good enough in a car. In an industrial vehicle maybe but in a car, no way. 

Sink and fan directly to the controller. I have more photos if you want to see. 

http://greenev.zapto.org/electricvw

Have a look around. 

Pete


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## lou-ace (Jul 21, 2009)

Well Blue, heat kills these controllers. I don't really know where the Mosfets are located but I've always thought that heat rises. So I mounted my fan above the unit along the heat sink casing. please see lou-ace in the garage. Now I've been told that I did it wrong and that the unit needs cooling form beneith. The under side of my unit is graced by road breeze while under way. But even on the hardest runs I've never felt more that just a little heat beneith my 1231c. so I would recomend a litle more research and mabey ask the good people at curtis. good luck.


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## Guest (May 10, 2011)

The mosfets are connected to the internal heat sink that is attached to the lower plate of the controller. The plate is then attached to the internal surface of the aluminum case. It is there that the heat is sinked out. Attach a sink to the bottom of the controller for the best heat removal. Put the fan on the finned heat sink. I can shoot you some photos of what a curtis looks like on the inside. The top of the case is going to do little at removing heat. It will remove some but not much. The main area is the bottom. It is important to install a proper finned heat sink. What else do you need to know? 

Pete 

Have you looked at other controllers and have you looked at the photos I have posted? Not sure why you are still asking questions on this subject. You need a good finned heat sink. Period. You need a good fan. Period. If you want your controller to live. You must use good quality thermal grease between the flat parts and you must verify that the surfaces of the sink and bottom of the controller are flat. Cut corners and you will pay the price. Period.


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## bluefxstc (Dec 29, 2007)

Thanks Pete

I always had a heat sink on the bottom and it seemed as hot as the sides of the case. I added 3 fans to the bottom heat sink over the weekend so I am glad to see it was the right location.

Thanks again for the help.
Bluefxstc


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## ElectriCar (Jun 15, 2008)

Curtis stopped making a sink for this controller. Mine overheats at 150-200A after less than 10 minutes in 85F heat with a 3/8" aluminum plate fanned by two fans underneath. I'm thinking of addign a fan to cool the top and sides a bit since they read about 125F when I checked them just after stopping. I LOVE that sink on your kelly gottdi!


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## Guest (Jun 22, 2011)

Go on Ebay to buy some extruded aluminum finned heat sinks. You can get it to the size you need then take it to the machine shop to drill out mounting holes. Drilling into the fins requires special drilling tools I just did not have. Most of the fins on the old controller I had were not wide enough to allow drilling and mounting without cutting into a fin. The machine shop did a bang up job for me on that one. That and a good large high speed and high volume fan is what is needed to pull that heat away. Do not use flat plate. It just won't allow the heat to move away fast enough. Under low loads like 50 amps or less it may be just fine but at the levels we need for cars it just won't do. Don't waste your time with other avenues of cooling. Get a sink and mate it to your controller. Curtis and other companies can't make them as each use is different. So get a good thick based and deep finned sink. 1 to 2 inches deep should be just fine. I'd go for the 2" or more if you can. But a fan on the sink blowing into the fins is a must. 

Pete 


Yeah! like that huge thing the Kelly sits upon now? It should keep it ice cold. Well not exactly that cold but it should do just fine. My other one never ever ever ever got too hot to handle after I put on the sink and fan. EVER. 

Pete


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## Guest (Jun 22, 2011)

Fins create a super large amount of surface area to allow for cooling. It is an absolute must and no skimping here. It is a major investment. Don't smoke it. They cost way too much.


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## Guest (Jun 22, 2011)

If you can run your controller at a voltage lower than max. So a 144 volt controller should be run at 120 but not 144. If you need 144 then get a controller that will do more. It is always the best. Usually increasing the life by leaps and bounds. Keep the amp draw below the max too. Set cut back if you can so it wont go over the max and set your temp to cut back as well before it gets too hot. My controller can do this for me. Super smart controller. It will do what you tell it. 

Pete


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## ElectriCar (Jun 15, 2008)

Thanks man. I searched ebay but only found a zillion for cpu cooling. Nothing large enough for that but I'll keep trying. Did you save the seller to your favorites? Maybe I could contact them directly.


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## Guest (Jun 24, 2011)

Go to Ebay and type in the search engine: Large Heat Sink

You will find what you need.


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## gsmith191145 (May 1, 2011)

It is obvious that you need to have a high cfm fan blowing across your heat sink to remove the heat. 

Also you need a place for that dispelled heat to go. 

Also you can water cool it.

Or move it to the front of the vehicle to where the radiator was and make sure to grease the terminal ends to water proof it. ( I saw that done on a city electric vehicle. The controllers are typically placed in the back of the cars but in the city models they were moved to the front of the car to help with cooling.


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## ElectriCar (Jun 15, 2008)

I've installed a 4" duct connected to the place where the factory air intake got air and can't tell any difference. I did find the hood which was missing it's insulation was heating it up to over 110F while it was parked. I since installed a R4 foam insulation with a radiant barrier surface to help with that but it still has issues.

Last night, temps around 70F with the controller at same temp, I took a trip of 34 miles up the interstate and it still ran hot so yes I must install a finned sink. I have a small one not quite the area of the controller which I may try first. With fans I think it would do the job. Sink fins are about 30-35 mm but overall will be about 1/2" short on sides and 1" on length, each end.


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## EVfun (Mar 14, 2010)

"Install" the Cursit 1231 in the freezer and install a Soliton?


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## tomofreno (Mar 3, 2009)

> I did find the hood which was missing it's insulation was heating it up to over 110F while it was parked. I since installed a R4 foam insulation with a radiant barrier surface to help with that but it still has issues.


 Where did you get the insulation with radiant barrier? I've noticed my controller heats to about 37C on a hot summer day since it is right under the hood, and have been looking for insulation like that.

I have a 250 cfm 5" axial fan mounted on the 2" deep fins of a heat sink which is the same size as my controller. When the car is moving, there is no difference in controller temperature with the fan off or on since air flows across the fins from the front of the car, but it does cool it 2 or 3C when stopped at a traffic light (compared to fan off).


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## ElectriCar (Jun 15, 2008)

Tom it came from home depot. It's a 1/2" foam board with foil on both sides but one side is white. Same stuff I lined my battery box with.


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## ElectriCar (Jun 15, 2008)

I'm in contact with a repair shop that says they can upgrade the thing and said I probably wouldn't need a fan afterward, only a good heatsink. A 1000A upgrade includes replacing the 50A mosfets with 130A ones, replacing the diodes with higher current lower resistance ones which is where some of the heat comes from if not most of it. I have no idea what the diodes purpose is in there. 

I was referred to the shop by the company I bought it from as they are an authorized repair shop for Curtis controllers so I trust they know what they're doing. They've been offering this upgrade for a couple of years that I'm aware of and the cost is $650.00 So for roughly $2200 I'll have a 1000A controller!


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## Guest (Jul 3, 2011)

Don't tell me your seriously thinking of taking this guys advice that you won't need a fan on your 1000 amp upgrade. That is more reason to put a good fan on that heat sink. Thick bodied finned heat sink right?


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## ElectriCar (Jun 15, 2008)

Well I already have two fans but am just now adding the sink. You know this unit exterior has fins, though very small, down the sides and top but I haven't a fan on them, only free moving air. 

If I'm cruising the interstate at 70 on flat ground I'm drawing something over 100A, probably closer to 125-150 but around here there aren't many flat places to document it. In any event, climbing hills at that speed and maintaining it will go closer to 250-300A which could last for 10 seconds maybe. 

I will be much more satisfied with the ability to exceed 500A to pass or such for short periods. My motor of course can't handle that current for very long but it would only be for seconds anyway.


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## Guest (Jul 3, 2011)

Fans go on the sink, not the case. Why can't your motor handlemore than 500 amps? Don't you have cooling for your motor? What soze is your motor? Kind?


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## ElectriCar (Jun 15, 2008)

I've always fanned the heat sink but it was merely a flat plate. Now I've added this large sink and will have fans on the bottom.

The comment about fanning the housing is because it has probably 3/16" fins but I've never had a fan on it but I'm sure it would help somewhat. I saw one guy who built a shroud or tunnel in which he put the controller and mounted a fan atop the shroud to blow on the fins forcing air through the tunnel. He doesn't have a fan on the bottom but I doubt the housing cooling will be enough as the thick bottom will contain most of the heat.


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## ElectriCar (Jun 15, 2008)

Just got my truck back running after getting the controller upgraded to 1000A. I installed the heat sink but left the fans off for now. Dave Mosher said I likely wouldn't need the fans with the heat sink AND his new mod which includes low resistance diodes, only 1/3 the OEM resistance. Runs much cooler now. 

I tested it yesterday sans fans and after driving around the controller temp was only 110 after lots of stop and go driving but the outside temps were about 85F. If I can do that at 100F then I'll leave the fans out altogether!

Oh, and let me tell you, it's scary fast and will INSTANTLY spin the tires!  Unbelievable torque if I step on it. This thing is NOTHING like the original controller. I'm seriously concerned if I wanted to I could break the factory T5 NWC transmission!


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## gsmith191145 (May 1, 2011)

What is this shop that upgraded your controller? I have been interested in upgrading to a soliton jr but if they can upgrade my curtis that would be awesome.


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## ElectriCar (Jun 15, 2008)

Here's his email. domosher at mchsi dot com.


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## dynoguy (Jun 29, 2010)

I am looking at fans at Frozen CPU and Grainger. I can spend $35 at Frozen for a fan or would I better off getting one from Grainger for $85 that is about the same size? Or is there a better place to look? Thanx.


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## sonicj (Mar 17, 2010)

check out the surplus houses.... bgmicro, electronicgoldmine, skycraft, mpja, allelectronics, etc. 
-sj


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