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Jul 30, 2021, 04:10 PM
312mph FPV
OMEGOOLIEBIRD's Avatar
Quote:
Originally Posted by Knife Liddle
Well we'll probably never know for sure because no one is going to do the level of testing and data collection needed to prove or disprove the theory.

I think that a thin wafer like this that actively draws heat from the fets and moves it to the heatsink certainly isn't going to cause the esc to run hotter.
It is 2 aluminium wafers with a layer of insulation in between and a tiny transducer in the middle. The layer of insulation is the concern, as it covers the majority of the area. If the top and bottom were thermally coupled, the transducer would have no effect in heating one plate and cooling the other. Hence the insulation. The transducer will offer a tiny bit of active cooling, at the expense of the natural cooling of the heatsink. The heatsink offers far more thermal transfer than the transducer's effect. An interesting experiment though.
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Jul 30, 2021, 04:17 PM
Registered User
Quote:
Originally Posted by sneu
There is no "program card" for the APD controllers--you can turn the synchronous rectification on or off using the configurator. in the HV Pro series controllers. With the XXF3 controllers you need to have the newest version of firmware installed and use the newest version configurator to access this and other features. If you don't want to fool with firmware updates you can get similar results by setting up a ramp for your throttle channel in your Tx that slows down the "off" response time.

Steve
Can this be done with a DX8 gen 2 and if so how?
Jul 30, 2021, 06:01 PM
Lee Liddle
Knife Liddle's Avatar
Quote:
Originally Posted by OMEGOOLIEBIRD
It is 2 aluminium wafers with a layer of insulation in between and a tiny transducer in the middle. The layer of insulation is the concern, as it covers the majority of the area. If the top and bottom were thermally coupled, the transducer would have no effect in heating one plate and cooling the other. Hence the insulation. The transducer will offer a tiny bit of active cooling, at the expense of the natural cooling of the heatsink. The heatsink offers far more thermal transfer than the transducer's effect. An interesting experiment though.
My understanding is that the heat sink is needed to cool the hot side of the transducer.

I understand what you are saying that there in no thermal connection between the two plates.

Of course one very important variable is the ambient air temperature that is absorbing heat from the heatsink, for obvious reasons.

My thinking is that the action of the transducer will act very much like a thermal connection and the as far as the esc is concerned, it is flying in very cool weather. As long as the fets are in contact with an aluminum plate that is very cold, does it matter how the plate gets cold? I don't think the esc will know the difference.

Now if the esc develops so much heat that it overpowers the transducer, then it would start to behave like it has an aluminum plate that is wrapped in heat shrink.
Jul 30, 2021, 06:04 PM
cogito ergo zoom
Parallax's Avatar
Please go learn the differences between the three forms of thermal energy transfer and how they relate to finned alloy structures. Then, learn what it takes to (actually) transfer thermal energy to ensure passive thermal (aluminum in this case) conductors require to be anywhere near effective.

There's enough online info to come to the correct conclusion...
Jul 31, 2021, 04:06 AM
Lee Liddle
Knife Liddle's Avatar
Quote:
Originally Posted by Parallax
Please go learn the differences between the three forms of thermal energy transfer and how they relate to finned alloy structures. Then, learn what it takes to (actually) transfer thermal energy to ensure passive thermal (aluminum in this case) conductors require to be anywhere near effective.

There's enough online info to come to the correct conclusion...
At your suggestion I did just that.

What I found is that one of the most common applications for these thermoelectric wafers is to provide cooling for all kinds of heat producing electrical components. Most notably they are already being used to " cool the mosfets used in dc motor controllers ".

So, cooling mosfets IS one of the main applications for this little device.

I would imagine that the main reason that manufacturers of our ESC's are not already using these is to reduce the cost and complexity of our toys.
Maybe it's overkill and we can get by without using these to help cool our equipment (we do have easy access to an extremely fast moving airflow), BUT these devices are in fact designed to be used exactly as I'm using them here.

It seems to me that some might benefit from thinking a little outside the box instead of spending their energy trying to theorize why someone else's idea won't work.
Last edited by Knife Liddle; Jul 31, 2021 at 04:12 AM.
Jul 31, 2021, 04:32 AM
312mph FPV
OMEGOOLIEBIRD's Avatar
Quote:
Originally Posted by Knife Liddle
My understanding is that the heat sink is needed to cool the hot side of the transducer.

I understand what you are saying that there in no thermal connection between the two plates.

Of course one very important variable is the ambient air temperature that is absorbing heat from the heatsink, for obvious reasons.

My thinking is that the action of the transducer will act very much like a thermal connection and the as far as the esc is concerned, it is flying in very cool weather. As long as the fets are in contact with an aluminum plate that is very cold, does it matter how the plate gets cold? I don't think the esc will know the difference.

Now if the esc develops so much heat that it overpowers the transducer, then it would start to behave like it has an aluminum plate that is wrapped in heat shrink.
Quote:
Originally Posted by Knife Liddle
At your suggestion I did just that.

What I found is that one of the most common applications for these thermoelectric wafers is to provide cooling for all kinds of heat producing electrical components. Most notably they are already being used to " cool the mosfets used in dc motor controllers ".

So, cooling mosfets IS one of the main applications for this little device.

I would imagine that the main reason that manufacturers of our ESC's are not already using these is to reduce the cost and complexity of our toys.
Maybe it's overkill and we can get by without using these to help cool our equipment (we do have easy access to an extremely fast moving airflow), BUT these devices are in fact designed to be used exactly as I'm using them here.

It seems to me that some might benefit from thinking a little outside the box instead of spending their energy trying to theorize why someone else's idea won't work.
I am not trying to wet your fire, but once you have bonded this to the ESC there is no turning back. It is worth doing some basic calculations to see if it will 'ball park' work.

A peltier transducer requires a current to cool, and as well as the heat transferred during the cooling process, you have to loose that input power as heat too. So you are adding heat to the system, so you may actually need a bigger heatsink. It would be interesting to know the wattage of the transducer, as based on an efficiency of around 10-30% it would be possible to roughly work out how much heat it will pull.
Last edited by OMEGOOLIEBIRD; Jul 31, 2021 at 04:51 AM.
Jul 31, 2021, 10:26 AM
Lee Liddle
Knife Liddle's Avatar
Thank you. My last sentence wasn't directed at you.

So, I have just attached it with tape designed for that purpose for now, so it is reversible if needed.

Here are the specs. I'm not an EE so I'll have to rely on someone else to do the calculations. What I do know is that it transfers heat to the heatsink quickly so that is working. Also the cold side gets fairly cold and quickly too. So the fets are going to think it's pretty cold outside.

This really is just an experiment and not directly related to this esc, so I don't want to derail the thread any further. If I decided that it deserves a thread of it's own, I'll put a link here so those intrested can find it.

Thanks for your input. Lee
Last edited by Knife Liddle; Jul 31, 2021 at 10:41 AM.
Aug 01, 2021, 02:16 AM
Registered User
Atomic Skull's Avatar
If you're going to use the FETs as-is (no sanding) then a thermal pad is your best option. I'm using 1.5mm thermalright pads and they work very well.
Aug 01, 2021, 09:00 AM
312mph FPV
OMEGOOLIEBIRD's Avatar
Quote:
Originally Posted by Knife Liddle
Thank you. My last sentence wasn't directed at you.

So, I have just attached it with tape designed for that purpose for now, so it is reversible if needed.

Here are the specs. I'm not an EE so I'll have to rely on someone else to do the calculations. What I do know is that it transfers heat to the heatsink quickly so that is working. Also the cold side gets fairly cold and quickly too. So the fets are going to think it's pretty cold outside.

This really is just an experiment and not directly related to this esc, so I don't want to derail the thread any further. If I decided that it deserves a thread of it's own, I'll put a link here so those intrested can find it.

Thanks for your input. Lee
Ok, Last comment from me on the subject too then for now, but please keep us updated on your results, it is very interesting.

Looking at the specs, 50-60w of refrigeration is quite a lot! Assuming you have ample cooling on the physical heatsink to get optimal conditions for the transducer to operate at max efficiency, it should transfer a good amount of heat! I'm still not sure of the advantage as the heat still has to go out to atmosphere through the heatsink, with the added heat created by the power applied to the transducer. But maybe it will actually make the ESC run at a lower temperature than it would through a heatsink alone.. That would be interesting to find out! Presumably there is a tiny efficiency gain the colder a current path gets. This only applies up to 60w of heat throughput, then, like you said, it will hit a brick wall and heat up uncontrollably.
Aug 01, 2021, 10:32 AM
Lee Liddle
Knife Liddle's Avatar
Thanks again for the input. I bought them on a whim while looking for heat sinks because these ESC's come without them. I was shocked how cold the cold side got and decided to give them a try. I'll start a thread in the original edf forum (not foamy, large, or micro). I'll do a few simple bench tests and see what kind of temps the esc records with and without the transducers. One nice thing is that we always have a reliable 12v source of power onboard our edf jets so it doesn't add weight and only a little complexity.
Aug 01, 2021, 07:06 PM
Registered User
Atomic Skull's Avatar
My solution was these heatsinks from ebay which are a perfect fit over the FETs and a 1.5mm thermalright pad intended as an upgrade for the silicone heat pads on VGA chipsets and power mosfets in laptops. They are held in place by clips made from 9/16 cable stables (I cut the pointed ends off and smoothed them). I insulated the center with a coat of marine epoxy though this is actually not needed because the center of clips doesn't come anywhere near the PCB. To prevent the clips from vibrating loose I put a small drop of epoxy on the tips of the clips, this holds them in position but could be removed if needed.



Note that this stuff is more like stiff modeling clay than a silicone pad, it has some springiness but it conforms to the surface it's pressed against. In order to get the clips over the heatsinks without too much fuss I placed the assembly under a press and very gently squeezed it first which conformed the pads to the FETs before the clips were fitted (the clips squeezed it all together nicely after this)

Also, I highly recommend using a connector on the throttle/telemetry lead it makes maintenance so much easier. you can just disconnect the lead and remove the whole ESC without needing to remove the lead from the airframe and re run the wiring later. Any 2.54mm pitch connector will fit the holes in the PCB. I used a ampmodu latching connector but a mini-PV board socket could also be used and would mate with and retain (by friction) servo connectors perfectly.

https://www.digikey.com/catalog/en/p...s-series/20205

The female plug might look familiar:

https://www.digikey.com/en/products/...0y8ALABkAYg0ZA
Last edited by Atomic Skull; Aug 16, 2021 at 11:43 PM.
Aug 01, 2021, 07:40 PM
Lee Liddle
Knife Liddle's Avatar
Nice job. Very clean work.
Aug 09, 2021, 12:03 AM
New to this whole thing...
Quote:
Originally Posted by OMEGOOLIEBIRD
I'm still not sure of the advantage as the heat still has to go out to atmosphere through the heatsink, with the added heat created by the power applied to the transducer. But maybe it will actually make the ESC run at a lower temperature than it would through a heatsink alone.. That would be interesting to find out! Presumably there is a tiny efficiency gain the colder a current path gets.
Peltier coolers are commonly used to cool computer components when overclocking, as they will keep the components cooler under the same load than the same heatsink applied directly to the components.

The heatsink is going to be hotter, but heatsinks can transfer more heat to the air when the temperature difference is greater.

The biggest thing is going to be making sure that there's enough airflow for the heatsink to do it's job properly since as you say there will be additional heat being generated.
Aug 09, 2021, 02:18 AM
Lee Liddle
Knife Liddle's Avatar
That's what my "seat of the pants" engineering was telling me. The fact that we have extremely high volumes of airflow on the outside of the aircraft and even higher inside the ducted fan system means that we can plenty of cooling air for the cost of a little bit of added drag.
Aug 10, 2021, 07:58 AM
Registered User
Lloyd_D's Avatar
Does anyone have any firmware for the 80A which has maximum braking and fast start up like the F5B firmware?


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