Best way to connect/attach a watercooling plate 25*30mm to a BLHeli ESC 70a 21*42mm for most efficiency?

[Christophe]

Hi, What is the way to connect/attach this watercooling plate 25*30mm to this BLHeli ESC 70a 21*42mm to get the most cooling efficiency?

• Water-cooling plate (30.5x25mm): https://www.aliexpress.com/item/1005001807716093.html?skuId=12000017701193167

• BLHeli ESC 70a board 21*42mm: https://www.aliexpress.com/item/1005002438042950.html

 

[Christophe]

Thermal adhesive?
Though that's pretty permanent

Thermal pads and cable ties?
Thermal pads and bit of glue around the edges?

I have searched for thermal pads, do you think this one could do the job: https://www.aliexpress.com/item/1005005800922381.html?skuId=12000034398791447 (I need to cut it to size)
Which pad type and thickness would you recommend for my use?
I am also wondering if the pad will be able to "fill" the holes in the design of the built-in heat-sink of my BLHeli board.

How does the board interface?

Id be tempted to cover the underside with a rubber insulative barrier and then use 2 pairs of bars with threaded rod and nuts as a rudimentary clamp system.

This board will interface on the right side with 3 cables and on the left side with 2 cables. I have found an image to illustrate this and the cable size:

In this image, heatshrink is used I wondering if it is enough to hold a thermall pad in place though I like the simplicity of it, is there a way to improve this?
Do you have an example of this "cover the underside with a rubber insulative barrier"? I cannot see what with is.

 

[Christophe]

Shrink wrap will hold it in place but wont apply much clamping force. You could perhaps shrink wrap it THEN use some rigid bars, threaded rod and nuts to apply some clamping force. A few zip ties might achieve the same effect! You would have to be careful how much force you apply and onto which components it applies to on the underside of the PCB.

The shrinkwrap seems to be the expected solution though? Try it and see if it works well enough.

I was also worried of it not being enough hold enough firmly with shrink wrap.
Your concerns about the other side of the PCB boar makes sense, I am worried the heat shrink might limit the natural heat dissipation on the other side of the

Is the water block being applied
Directly to the silver heatsink already on there?
If so get a couple of different thicknesses
To account for holes or indentations
Or make sure to get more pads than needed
And slice little bits off and fill holes/indentation first
What thickness would only be a guess
No experience with one of those at all
I would probably get 1.5mm and 2mm
They're Cheap enough anyway

Good question, I am actually wondering if such heatsink can be removed? If it is possible, I would prefer removing it to be able to place the watercooling directly on the board.
If it is not possible, I need to place the water cooling on top of it. Is thermal paste able to fill the holes/indentiation of already present heatsink? I have neved used one til now. This might be necessary before applying the thermal pad.

 

[Christophe]

Yeah ideally I would remove the factory heatsink if possible
But then you may be similar to gpu waterblock
Ie needs more than 1 thickness thermal pads
Plus it might be stuck on with thermal adhesive
That would rip stuff off trying to remove it

From the picture they look like shallow indentations
I would think filling those with thermal paste
Then applying thermal pads would work
Can't guarantee it
But would I personally try that
Yeah have to say I would give it a go

I am thinking about flling the holes with this https://www.aliexpress.com/item/1005005812914345.html?skuId=12000034441714470
With my water-cooling placed on top, would is be a good idea to wrap the thermal pad below around the whole board, on top and on the bottom? instead of just adding it to the top?
The board might also get some heat from the bottom, even though less.

How much heat are you expecting to dissipate?

If the device in normal operation is passively cooled what is it you are doing that requires water cooling?

The image of a shrink wrapped solution, who has produced that? Is that the accepted/proven way of doing what you want to do?

Is there a reason you need water cooling over just pointing a high CFM/Static Pressure fan at the existing heat sink? (Noise, available airflow?) You could also increase the surface area of the existing heatsink with semi permanent additional heatsink application?

Its hard to really grasp what your objectives are and what a sensible solution might look like

This board is normally used on a drone, so a lot of airflow goes naturally over on it when in use. You can see it as an active cooling system in fact.
Cooling this board is very important because quite a lot of energy goes through it.
I want to use this board inside a 30cm small boat, where there is no airflow at all, so I need to use water to keep it cool.
The shrink wrapped on the photo above is more an easy and cheap way than a solution. I am afraid the board, thermal pad and watercooling plate might not be enough in contact with it as the boat vibrates when in use.

 

[Christophe]

It is an opened loop system, water will come from the external environment, via the impeller and then released to the lake.
I am going to use the boat on non salty water. So there is no salty water issues.
Vibration inside the boat is important that's why I am concerned about this water-cooling to stay in place and prevent the ESC board from overheating.

 

[Christophe]

Heatshrink and cable ties should be secure

I am not a fan of using cable ties in this situation as:
a/ the pressure would come from the corners which is not good for the PCB
b/ and not so good for the thermal conductivity as well as the PCB might bend a little causing less heat transfer
c/ cable ties looks a bit home improvement

Instead of cable ties, is there any way to get or do a clamp (something looking like the yellow part on each side of the image below) that could be added on the side to add some vertical pressure instead?
I understand that rod and thread can do that, but I have no idea how it looks do you have example? In my situation, weight and place is a premium so it needs to be as small/light as possible.

In the schema I have done, I forgot to represent the built-in passive heat sink that comes on top of my PCB board and that can certainly not be removed.

As sin_chase mentioned what about impurities/detritus/contamination
From the water?

That's actually an issue I don't know who to solve. This could be problematic because, contrary to a full-scale skidoo, where tiny debris is insignificant, given the size of my boat just a duckweed is an issue (for the cooling system as well as the impeller).

And is the impeller submerged?
Watercooling loops we never use the pump dry
So just curious if impeller is submerged
Or there's a way to prime it

Sorry, I do not understand the question, can you specify what you mean by "submerged" and what "way to prime it"?

 

[Christophe]

Fair point cable ties may put more pressure
On the edge
Than downwards pressure
Have a look for mini woodworking clamps
There's various types and a lot are available in plastic to save weight

I am thinking from a pc watercooling point of view
Where the pump/impeller should always have
Water/coolant in it before being turned on
It may well be this isn't an issue with a boat
I have no experience of boats/jetskis etc full size or rc models
In a pc we "prime" the pump by having a reservoir feed it

So priming means inserting the liquid for the 1st time within the water-cooling system. Is that correct?

2 lengths of aluminium C profile, some captive bolts and nuts would be a rudimentary and relatively lightweight clamp option. Still the same consideration as to what you clamp over on the PCB to avoid damage however.

You could even consider integrating the clamp into a fixing system in the boat and get dual purpose

Do you have an image of the aluminium C profile you are considering? I haven't seen one yet.
You are correct that I also need to take care of the PCB. Using a part inside the boat is a good idea.


I am considering another solution to hold the water-cooling block / thermal pad / PCB well together: is there some thermal conductive single-sided adhesive tape? I could use it to keep this together. The force would be better spread around all parts than a cable tie and resist boat vibrations.