Heat Sink

ESC too hot, problem of high temp cut off after 15mins run under sunlight,
done a small surgery to it:-

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点解直接換把更強力風扇(如5V電腦仔風扇), or 由接收取電?
師兄用幾多T Motor, 何解會過熱既?
咁樣吹會不會做成'擾流'ya?

師兄 , 我想問下你啲魔術貼係邊度買？我之前買個啲太實...

nice job, pretty neat and cool  !!
However as suggested by other brother, use a hi power fan may be more simple  

原帖由 rk2 於 2008-9-5 09:39 發表

                               
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nice job, pretty neat and cool  !!
However as suggested by other brother, use a hi power fan may be more simple  

I thought of using higher power fan for better cooling. But figured out the cooling rate is limited by the heat sink area, rather than the fan air flow speed. Because cooling related to both temperature difference (between surrounding air and heat sink) and surface area. While the air flow is already fast enough to bring out hot air, area is then my choice.

After adding the new heat sink, surface area around tripled, so the cooling rate increased.



Heat Convection: Gr ~ L^3  -> Convection Cooling increases power of 3 when the Characteristic Length increases

[ 本帖最後由 swswsw 於 2008-9-5 12:19 編輯 ]

原帖由 michaeltam 於 2008-9-5 07:17 發表

                               
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点解直接換把更強力風扇(如5V電腦仔風扇), or 由接收取電?
師兄用幾多T Motor, 何解會過熱既?
咁樣吹會不會做成'擾流'ya?

I have installed one fan for motor, powered from receiver already. performance not so satisfied, thinking how to improve.....

9T - Hobbywing Brushless set
Off-road Evening -> no overheat, very good acceleration.
Off-Road run while noon time -> overheat after 15mins
Reason is temperature difference between heat sink and air smaller, so cooling rate is smaller in noon time.

The cooling fan air flow should not in any way affect the car motion..as it is too weak in comparison

原帖由 terencelyl7411 於 2008-9-5 09:02 發表

                               
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師兄 , 我想問下你啲魔術貼係邊度買？我之前買個啲太實...

Cut it into half and just use this half in the Body side!!.... and keep the original width in the shell side...

So the 魔術貼 will not pull the paint out from the shell..and less strong

[ 本帖最後由 swswsw 於 2008-9-5 12:44 編輯 ]

原帖由 swswsw 於 2008-9-5 12:36 發表

                               
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I have installed one fan for motor, powered from receiver already. performance not so satisfied, thinking how to improve.....

9T - Hobbywing Brushless set
Off-road Evening -> no overheat, very ...

yes. you are right

Test Result in TKO today, (similar hot noon sun) :

Three separate continuous runs with 4000mAH Li-Po 25C battery. No high temp cut this time anymore. All runs till the battery-low cut.

Next Step is to deal with Motor over-heat issue, as it will de-magnetized after some time.....  thinking how to do...