When cooling a motor which way is better?

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parcou

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Arrma RC's
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Looking for newbie knowledge or discussion on what you all have experienced. I have this motor on my Big Rock BLX. Really trying to not focus on how I power the cooling but in respect to cooling which is better heatsink or not.

This motor has silver rings around it I assume the rings are for releasing heat (??), is cooling better using the heat sink pictured that holds the fan? Or is cooling better using a Powerhobby fan motor mount to let the fan blow directly on the motor without heatsink?

Added info: After two runs on 3S, 80F day outside, motor temps at highest right now to date 140F

Motor: 3674, 2650kv
1654148085886.png


Current heatsink and fan and fan is powered separaetly
1654148564183.png



Using one of these on my Kraton EXB with two GC fans so would be no issue with one fan. Or, using no heatsink would this be better?
1654148848531.png
 
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Cooling is 2 things

1. Surface area. So a large heat sink with multiple fins, to create this surface area.

2. Air flow to remove heat through the heat sink. Contrary to popular belief you want the fan to blow air up off the motor not on to it. This will draw the heat away. The air flow will draw cool air back over the heat sink to help continue the cooling cycle 👍
 
Looking for newbie knowledge or discussion on what you all have experienced. I have this motor on my Big Rock BLX. Really trying to not focus on how I power the cooling but in respect to cooling which is better heatsink or not.

This motor has silver rings around it I assume the rings are for releasing heat (??), is cooling better using the heat sink pictured that holds the fan? Or is cooling better using a Powerhobby fan motor mount to let the fan blow directly on the motor without heatsink?

Added info: After two runs on 3S, 80F day outside, motor temps at highest right now to date 140F

Motor: 3674, 2650kv
View attachment 221062

Current heatsink and fan and fan is powered separaetly
View attachment 221064


Using one of these on my Kraton EXB with two GC fans so would be no issue with one fan. Or, using no heatsink would this be better?
View attachment 221065
Those silver rings are indeed cooling fins that act as a heatsink.
A heatsink works best when it has as much contact with the motor so it can conduct as much heat from the motor. In combination with a fan, the fan can cool the heatsink.
As the motor has the cooling fins, the red heatsink you have will only have contact with the fins, which is minimal, to conduct heat. There are heatsinks like that (Yeah Racing which I have on the 4985), which have openings so that the fan can push airflow towards the motor. Looks like your red heatisnk does not have openings, so in that case I would go for the Powerhobby one that allows the fan to push the airflow on the motor and between the cooling fins.
You can also use a thermal pad so that you can use the red heatsink to optimize contact between the motor en heatisnk, but I would go for the black Powerhobby one if I were you.
 
Cooling is 2 things

1. Surface area. So a large heat sink with multiple fins, to create this surface area.

2. Air flow to remove heat through the heat sink. Contrary to popular belief you want the fan to blow air up off the motor not on to it. This will draw the heat away. The air flow will draw cool air back over the heat sink to help continue the cooling cycle 👍

Suck or blow is not the simple answer, it boils down to the temperature of the air flowing through the heatsink, the speed of flow and the contamination that can build up. So the simple answer is the coolest air, the best airflow and the least contaminations.

Also one thing to note, you will destroy fans much easier running them upside down. The fan blades do have up and down movement, on a good landing the blades will quite literally pop out of the housing.

Those silver rings are indeed cooling fins that act as a heatsink.
A heatsink works best when it has as much contact with the motor so it can conduct as much heat from the motor. In combination with a fan, the fan can cool the heatsink.
As the motor has the cooling fins, the red heatsink you have will only have contact with the fins, which is minimal, to conduct heat. There are heatsinks like that (Yeah Racing which I have on the 4985), which have openings so that the fan can push airflow towards the motor. Looks like your red heatisnk does not have openings, so in that case I would go for the Powerhobby one that allows the fan to push the airflow on the motor and between the cooling fins.
You can also use a thermal pad so that you can use the red heatsink to optimize contact between the motor en heatisnk, but I would go for the black Powerhobby one if I were you.
Yup, that motor already has cooling fins and as such adding that heatsink to it actually is worse than not having one on it as it creates voids between the motor and heatsink where the hot air just sits. With ribbed motors you want a fan mount with smooth motors you want a heatsink with fan.
 
Cooling is 2 things

1. Surface area. So a large heat sink with multiple fins, to create this surface area.

2. Air flow to remove heat through the heat sink. Contrary to popular belief you want the fan to blow air up off the motor not on to it. This will draw the heat away. The air flow will draw cool air back over the heat sink to help continue the cooling cycle 👍
#2 is incorrect. Every application of the heatsink and fan in electronics the fan is blowing air onto the heatsink. Not drawing air from it. For example, look at the fan on any ESC.

Proper heatsink and fan setup
 
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Cooling is 2 things

1. Surface area. So a large heat sink with multiple fins, to create this surface area.

2. Air flow to remove heat through the heat sink. Contrary to popular belief you want the fan to blow air up off the motor not on to it. This will draw the heat away. The air flow will draw cool air back over the heat sink to help continue the cooling cycle 👍
On a hot day after working outside, do you stand in front or behind a fan?
 
Suck or blow is not the simple answer, it boils down to the temperature of the air flowing through the heatsink, the speed of flow and the contamination that can build up. So the simple answer is the coolest air, the best airflow and the least contaminations.

Also one thing to note, you will destroy fans much easier running them upside down. The fan blades do have up and down movement, on a good landing the blades will quite literally pop out of the housing.


Yup, that motor already has cooling fins and as such adding that heatsink to it actually is worse than not having one on it as it creates voids between the motor and heatsink where the hot air just sits. With ribbed motors you want a fan mount with smooth motors you want a heatsink with fan.
+1
I found that a fan blowing directly at a motor has best cooling effect. Less "Heat soak" when using NO HS. Heat soak slows down the thermal heat transfer due to increased mass of the HS. So cool down recovery can vary. Based on my experience.
All BLX alloy motor Cans are Heat Sinks by design. Some are finned for better cooling efficiency.
I think HS are overrated and just became a thing. More of a Crutch/way to mount A Fan.
A motor can be used without a fan, using just a HS and this might better than nothing. Some Arrma rigs only come with a HS and No fan.
I always had best cooling without a HS using a Fan and mount only.
Trial and error and its application ( Speed running versus Bashing) dictates what will work best for you. Temp gun in hand.
 
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I run the same style motor with the Powerhobby fan mount on most my 3s cars and will be converting the other two soon. On my two, 6s cars I use the power Hobby fan mounts on the stock motors. The fan mounts seem really solid and work better than the stock heat sink, especially with a ribbed motor. I believe the ribbed motor and heat sink combination will actually make things worse.

All I need right now is more powerful fans. I think you and I have similar heat issues with our local weather. It’s really hard to keep these things cool sometimes when it’s 90f by 10 a.m, Triple digits by noon and still 90f at 6pm with 90%+ humidity.
 
I run a few of those powerhobby fan mounts. I love them. Keeps the fans up off the motor for better flow, plus has a bit of sink action. I have 2 on 4985's, 1 on a stock 2150kv, and 1 on a 14 series castle and have yet to have a problem.
To my knowledge the Powerhobby fan mounts are the only ones of this type of clamp fan mounts that can accommodate two fans and not just one. How is it that Powerhobby was the only manufacturer smart (or dumb) enough to put two extra holes in the same mount? Yeah, technically you can sell twice as many if it only mounts one, but I'll go out of my way to get the Powerhobby one just so I can mount two.
 
On the kraton. I use a 40mm fan. Sans 40mm. Along with a powerhobby fan mount.. temps never reach above 130s. Without the fan 150-160s. I don't use a "heatsink"
Don't have any photos of it. But it's space from the motor to blow the entire exterior instead of just one side.

My limitless. Fans are mounted about a inch and half away. Custom 3d printed part. And the air flow is incredible compared to having it sit directly on the motor. It blows the entire motor to cool down

20220407_213621.jpg


20220420_192509.jpg
 
I run the same style motor with the Powerhobby fan mount on most my 3s cars and will be converting the other two soon. On my two, 6s cars I use the power Hobby fan mounts on the stock motors. The fan mounts seem really solid and work better than the stock heat sink, especially with a ribbed motor. I believe the ribbed motor and heat sink combination will actually make things worse.

All I need right now is more powerful fans. I think you and I have similar heat issues with our local weather. It’s really hard to keep these things cool sometimes when it’s 90f by 10 a.m, Triple digits by noon and still 90f at 6pm with 90%+ humidity.
Texas summers are tough. When I lived in Austin, during the summer our AC only shut off for about a half hour around 4AM. 🤘TEXAS BABY!! I miss living there.
 
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+1
Placing a Fan Flat against a motor or HS disturbs static pressure. This impedes Fan RPM's and reduces efficient air flow.
Placing the fan further away is better. Higher fan speed and cooling more motor surface area., Experiment with this and you will see. Temp gun always in hand. Only way to judge for yourself.
 
Texas summers are tough. When I lived in Austin, during the summer our AC only shut off for about a half hour around 4AM. 🤘TEXAS BABY!! I miss living there.
Yup, I love the heat but humidity sux over 80% and it’s almost always over 80%. We keep the ac on 78f. It’s enough to cool and dry out the air yet doesn’t jack the electric bill up so much.
Texas summers are tough. When I lived in Austin, during the summer our AC only shut off for about a half hour around 4AM. 🤘TEXAS BABY!! I miss living there.
Yay…it’ll be a fun weekend and even funner Monday 🥵
 

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Yup, I love the heat but humidity sux over 80% and it’s almost always over 80%. We keep the ac on 78f. It’s enough to cool and dry out the air yet doesn’t jack the electric bill up so much.

Yay…it’ll be a fun weekend and even funner Monday 🥵
Yeah humidity is teh suck. My brother-in-law worked at NASA and lived just outside of Houston on the Gulf coast and the humidity was suffocating. Austin was, comparatively speaking, pretty dry. The hottest day we had during my 8 year stay in Texas was 113°F. Countries on the Arabian peninsula probably laugh at that but that was plenty toasty for me.

"My blood is too thick for Texas. I've never been able to properly explain myself in this climate." -- Hunter S. Thompson, probably
 
Yeah humidity is teh suck. My brother-in-law worked at NASA and lived just outside of Houston on the Gulf coast and the humidity was suffocating. Austin was, comparatively speaking, pretty dry. The hottest day we had during my 8 year stay in Texas was 113°F. Countries on the Arabian peninsula probably laugh at that but that was plenty toasty for me.

"My blood is too thick for Texas. I've never been able to properly explain myself in this climate." -- Hunter S. Thompson, probably
I was born and raised in Houston. I hitchhiked to Alaska in ‘92 and didn’t come back to Texas till ‘12. I wanted out so bad… Thankfully my family had relocated to San Antonio meanwhile.

I love Thompson’s books. His writings alongside Jack Kerouac make reading fun.
 
I was born and raised in Houston. I hitchhiked to Alaska in ‘92 and didn’t come back to Texas till ‘12. I wanted out so bad… Thankfully my family had relocated to San Antonio meanwhile.

I love Thompson’s books. His writings alongside Jack Kerouac make reading fun.
Wow, that was a ballsy move. Tip of the hat good sir. And yeah, SA is far more bearable than Houston. Spent a weekend in SA when I got my permanent residency and found some really excellent Tex-Mex on the river walk.

Thompson was a truly unique nutter and his writings are awesome. "One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die."

I still need to catch up on some Kerouac. What book of his would you recommend?
 
To add to the discussion above:
1) air is a very good insulator (resistant to heat transfer) unless it's moving. That's the same reason why windows have multiple panes of glass (the center layer is stagnant air that is good at insulating).
2) a heatsink is used to create more area that air or liquid can pass against to pull away heat. Heatsinks only works for areas they have DIRECT contact with the heat source (motor) and good airflow.

In OP's case, the recessed rings on the motor can would create pockets of air that don't get good air movement if you added a heatsink. With that style of motor can, the best thing you can do is get a fan mount and blow it directly on the motor can. As also pointed out above, keep the fan mounted slightly above the motor to allow better flow around the can.
 
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Thx all very, very good feedback. What I was looking for will order the Powerhobby mount.


I run the same style motor with the Powerhobby fan mount on most my 3s cars and will be converting the other two soon. On my two, 6s cars I use the power Hobby fan mounts on the stock motors. The fan mounts seem really solid and work better than the stock heat sink, especially with a ribbed motor. I believe the ribbed motor and heat sink combination will actually make things worse.

All I need right now is more powerful fans. I think you and I have similar heat issues with our local weather. It’s really hard to keep these things cool sometimes when it’s 90f by 10 a.m, Triple digits by noon and still 90f at 6pm with 90%+ humidity.

Yes Sir you are right. I am a bit north in Memphis and you get hotter but the humidity in this delta of the Mississippi River is an oven. I feel ya, LOL
 
Thx all very, very good feedback. What I was looking for will order the Powerhobby mount.




Yes Sir you are right. I am a bit north in Memphis and you get hotter but the humidity in this delta of the Mississippi River is an oven. I feel ya, LOL
Oh…There’s two power hobby fan mounts. One is set up to run two fans and it’s the good one. The other thin one is utter crap. I accidentally got it first and it’s a throwaway because it cracks so easy.

Yeah, you’re humidity is just short of full-blown rain on a constant basis I believe 😂
I feel for you man! At least here we get the occasional dry desert feel, which I love.
 
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