Kraton Hobbywing 4985 1650kv cooling

M240i_bandit

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Hi Guys,

I couldn't find anything concrete on a search but need a little help - I've got an EXB with the Max6 combo/1650kv on 18T which seems to be running a bit warmer than I'd like (can't keep my finger on the can for more than half a second)

I bought a K8s heatsink and fan but I'm not sure it it'll fit - has anyone managed to successfully fit it? It fits around the can, and would need stretching over the fins which seems achievable - but I'm more concerned about the lack of clearance underneath the motor. Once it's on the motor it doesn't look like it'll be easy to pull off so a bit hesitant to just give it a go

On a side note how hot is too hot for these things? I'm estimating the can somewhere around 70C give or take

Cheers
Daven
 

DKPatriots

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I've heard that this fan and heatsink work on that motor, but I don't have one myself so I can't gaurantee it.

https://www.amazon.com/dp/B07ZPMTZX...abc_4TZR4DXNS6RZ0ZR6G0TQ?_encoding=UTF8&psc=1

The heatsink is designed for 40mm motors butncomes with four spacers that allow it to fit around larger cans.

Too hot is over 170-180F, which is about 75-82C. Past that and you risk the heat weakening the magnets. Guys like to keep them at or below 160F (about 70C) so that you have a bit of a buffer between the running temp and the max safe temp. As with many things in electronics, cooler is better.
 

M240i_bandit

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I've seen a couple of guys mention that, or something similar by Yeah racing - but I'm really struggling to get hold of anything like it here in the UK

My last resort I guess would be the Alza racing mount but my concern was it's not really a heatsink, just a fan
 

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I've seen a couple of guys mention that, or something similar by Yeah racing - but I'm really struggling to get hold of anything like it here in the UK

My last resort I guess would be the Alza racing mount but my concern was it's not really a heatsink, just a fan
Have a squiz on ebay and aliexpress mate. There are quite a few options - none direct, just look at the lowest cost postage. I bought my YR double fan cooler on ebay from US and only paid a few dollars postage. I'm also UK.
 

DKPatriots

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A fan may be all you need. The Hobbywing 1650kv has ridges on it, and a hestsink will only touch those ridges. Heatsinks work better when the can is flat is flat so that it gets better contact. Zip tieing two (or more if you want to) fans to the motor will lower your temps by a solid margin.

Heatsinks are great, but they are only as great as the solid contact they make with a hot surface. Fans are what do the actual cooling.

Case in point from computers... A heatsink on a CPU without proper mounting pressure and without thermal compound / paste between it and the CPU to fill in tiny gaps, will not cool effectively at all.

Heatsinks aren't bad for RC motors, but fans are where most of the cooling comes from.
 
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ErockPzyk

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Hi Guys,

I couldn't find anything concrete on a search but need a little help - I've got an EXB with the Max6 combo/1650kv on 18T which seems to be running a bit warmer than I'd like (can't keep my finger on the can for more than half a second)

I bought a K8s heatsink and fan but I'm not sure it it'll fit - has anyone managed to successfully fit it? It fits around the can, and would need stretching over the fins which seems achievable - but I'm more concerned about the lack of clearance underneath the motor. Once it's on the motor it doesn't look like it'll be easy to pull off so a bit hesitant to just give it a go

On a side note how hot is too hot for these things? I'm estimating the can somewhere around 70C give or take

Cheers
Daven
If you can't touch it already too hot from what I have learned. Why not change gearing?
 

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As mentioned before the EZRUN cans are basically heatsinks because of the Riffles on it.
A mounted heatsink will not make proper contact unless you fill the gaps with tons of thermal paste of pads n stuff...
I am in the same situation and evaluated this option, but it doesn't make much sense so I just ordered some descenRocket Fans on aliexpress and will mount 2 of them striaght onto the can.
 

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If you can't touch it already too hot from what I have learned. Why not change gearing?
Telling someone that is looking for a fan to cool his motor with the gears he wants to "just gear down" is like telling someone that is looking for a bigger intercooler to remove their turbo or turn down the boost. Yeah it's a solution but not what he wants.
 

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That was me.
As mentioned before the EZRUN cans are basically heatsinks because of the Riffles on it.
A mounted heatsink will not make proper contact unless you fill the gaps with tons of thermal paste of pads n stuff...
I am in the same situation and evaluated this option, but it doesn't make much sense so I just ordered some descenRocket Fans on aliexpress and will mount 2 of them striaght onto the can.
That's a bad idea thermal paste is meant to fill in tiny gaps and spaces, if your fill the fins with thermal paste it will be too thick and actually turn into an insulator.
 

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That was me.

That's a bad idea thermal paste is meant to fill in tiny gaps and spaces, if your fill the fins with thermal paste it will be too thick and actually turn into an insulator.
I just drilled holes through my heatsink so the air can pass through it to the motor, so efectivly making the heatsink into just a mount for the fans. It makes solid contact with the motor fins so it does cool a bit but the fans do most of the work.
 

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That was me.

That's a bad idea thermal paste is meant to fill in tiny gaps and spaces, if your fill the fins with thermal paste it will be too thick and actually turn into an insulator.
Excuzemeverymuch....corrected (y)

I've been using a thermal PAD for these heatsinks for years and that works great. It keeps the heatsink in place and draws a lot of heat from the motor:



https://nl.aliexpress.com/item/1005...earchweb0_0,searchweb201602_,searchweb201603_
 

ErockPzyk

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That was me.

That's a bad idea thermal paste is meant to fill in tiny gaps and spaces, if your fill the fins with thermal paste it will be too thick and actually turn into an insulator.

Telling someone that is looking for a fan to cool his motor with the gears he wants to "just gear down" is like telling someone that is looking for a bigger intercooler to remove their turbo or turn down the boost. Yeah it's a solution but not what he wants.
Just a suggestion no need to be a peepee bra lol
 

slick2500

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Excuzemeverymuch....corrected (y)

I've been using a thermal PAD for these heatsinks for years and that works great. It keeps the heatsink in place and draws a lot of heat from the motor:



https://nl.aliexpress.com/item/1005...earchweb0_0,searchweb201602_,searchweb201603_
Pads are different from paste, pads are designed to be so thick and compress where needed, paste is designed to be spread out in a thin layer.
 

FatCatRC

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Just a suggestion no need to be a peepee bra lol
What did I say to warrant being called a peepee lmao? I'm just saying telling someone to gear down to solve their heat problems is like telling someone to turn down their boost or use different heads. He wants that speed the gears he is using give him but wants to control his heat with a fan.... Wasn't being a peepee at all man just saying.
 

ErockPzyk

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What did I say to warrant being called a peepee lmao? I'm just saying telling someone to gear down to solve their heat problems is like telling someone to turn down their boost or use different heads. He wants that speed the gears he is using give him but wants to control his heat with a fan.... Wasn't being a peepee at all man just saying.
You don't have to comment on others opinions but you felt the need cause your a Richard. All good bro do u lmao
 

FatCatRC

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You don't have to comment on others opinions but you felt the need cause your a Richard. All good bro do u lmao
Dude it's a forum. It's what it's about. We all have opinions on here. No need to get upset and call people names. Have fun doing you and calling people names for suggesting something you don't agree with. (y) 🤷‍♂️
 

M240i_bandit

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Have a squiz on ebay and aliexpress mate. There are quite a few options - none direct, just look at the lowest cost postage. I bought my YR double fan cooler on ebay from US and only paid a few dollars postage. I'm also UK.

Good to know - Always thought it was a pain shipping things in from the US, but I'll probably end up doing this - do you find the fan speeds are high enough to give sufficient cooling?

A fan may be all you need. The Hobbywing 1650kv has ridges on it, and a hestsink will only touch those ridges. Heatsinks work better when the can is flat is flat so that it gets better contact. Zip tieing two (or more if you want to) fans to the motor will lower your temps by a solid margin.

Heatsinks are great, but they are only as great as the solid contact they make with a hot surface. Fans are what do the actual cooling.

Case in point from computers... A heatsink on a CPU without proper mounting pressure and without thermal compound / paste between it and the CPU to fill in tiny gaps, will not cool effectively at all.

Heatsinks aren't bad for RC motors, but fans are where most of the cooling comes from.

That's actually something i didn't consider, I was thinking about using a load of thermal paste but I tried it before on the MERV and the mess it left was horrible - Still haven't been able to get rid of the excess stuff round the edges


I was actually asking speficically for how to fit the K8s heatsink onto the 4985 & whether there's enough clearance under the motor - can't see that specifically being mentioned in any of those?

If you can't touch it already too hot from what I have learned. Why not change gearing?

From reading around before the build I actually thought 18T was pretty conservative as most are running 19T or 20T - I'm hoping to go up to get a bit more speed and bring the torque down so cooling is probably my only option now - I don't really find the 18T to be that fast

As mentioned before the EZRUN cans are basically heatsinks because of the Riffles on it.
A mounted heatsink will not make proper contact unless you fill the gaps with tons of thermal paste of pads n stuff...
I am in the same situation and evaluated this option, but it doesn't make much sense so I just ordered some descenRocket Fans on aliexpress and will mount 2 of them striaght onto the can.

I think as above the fans are probably the best way to go - I've tried thermal paste before and just hated the mess it leaves

Thanks for all the replies guys - Looks like the Arrma heatsink is going on Ebay and I'll just order something off Ebay
 
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