NEW - ESC vs ESC

[Nitros83]

After the first part I believed the CC made it better than KK

[Nitros83]

Originally Posted by Nitros83

After the first part I believed the CC made it better than KK

...

[Mercuriell]

Very informative and entertaining Tony - think you should have had de-ionised ice-cream in the cooler rather than water on those 100% throttle tests

Explains why peeps had such concerns about running the older ESC at lower throttle setttings some years ago and highlights the false sense of security some may have running a big chunky 160A ESC at only 1/4 rated load !

Hope you had some ear plugs in - those motors were screaming !!!

[Elios000]

any way you could test how well the governors hold on each esc?

[jamin_00]

Excellent. Looking forward to episode 3

[dna001]

It would be interesting to see the difference between governor mode and flat line throttle curves.
But you would have to find away to simulate unloaded blades being spun faster by air.

[Elios000]

a load is a load
and he has a great setup for that
im just interested in how well one ESC or another holds rpm and how fast they can react
what is making hte load isnt an issue

[dna001]

Originally Posted by Elios000

a load is a load
and he has a great setup for that
im just interested in how well one ESC or another holds rpm and how fast they can react
what is making hte load isnt an issue

A governor dose not just hold the blade speed up, it also has to stop the blades over speeding , so you would have to simulate the motor over speeding not just under load.

[Elios000]

well removing the load suddenly would do that
im sure our new friend here could come up with a way

[Mercuriell]

Best way to check the efficiency of a gov is from the rpm graph of a logger taken from a real flight experience - not sure how much a bench test would have to offer!

[Elios000]

could be fun to find out whats the most efficient settings so you set your gearing better

[Scallybert]

Originally Posted by Mercuriell

Explains why peeps had such concerns about running the older ESC at lower throttle setttings some years ago and highlights the false sense of security some may have running a big chunky 160A ESC at only 1/4 rated load !

I think you need to consider that a smaller ESC would also be running with the same throttle & PWM - so would be dissipating the same FW heat. The bigger ESC may well fare better, as it has bigger MOSFETs & heat-sinks.

[Mercuriell]

Originally Posted by Scallybert

I think you need to consider that a smaller ESC would also be running with the same throttle & PWM - so would be dissipating the same FW heat. The bigger ESC may well fare better, as it has bigger MOSFETs & heat-sinks.

Naturally. My point is that without AFW the size of the ESC and a low throttle setting may be falsely reassuring!

[fasse_sweden]

Actually what load is not that important. It's gearing or prop size and matching motor that counts. You got a lot more headroom with a160A esc than a 80A when "max" load is say 75A running at say 95% throttle. But if you gear the heli incorrectly and running about 50% throttle, both esc are struggling...

[Iceberg86300]

ub3r,

Do you have access to a load cell by any chance? It would be interesting to know the loads these are outputting at your test levels. And a load cell would constitute real world data, much better than using electrical power and converting using estimated electrical losses. Would just need a load cell that falls in the range of most of the testing, a pivot on the load motor (because mounting will always be the same, different length bars to get the load cell in the sweet spot, or a way to adjust length, and a data logger. There is software out there that turns your sound card into a datalogger. You seem pretty savvy electronically so it shouldn't be a problem. Or I have a device I could reprogram to give instant readings I made in college, but something you sweep data into the computer for room and load would be stunning in my eyes with what you already have.would give efficiencies, torque, horsepower curves, or just make sure you are testing esc's or motors at the same mechanical load.


We could actually have non-manufacturer load and efficiency data. Let me know if you would like me to work on some kind of setup for this. I've got a spare microcontroller that would be perfect, and programming that all I would have to do is add some serial chips to out put to the computer.

Steve

[JKos]

There are scales available with convenient data outputs, like USB. It would be nice to have some real efficiency data.

- John

[Mercuriell]

Interesting idea - I don't know much about load cells - how would you convert a rotary output from a motor to a strain gauge - would you have to have some sort of slipping clutch connected to a bending lever?

[Iceberg86300]

Originally Posted by Mercuriell

Interesting idea - I don't know much about load cells - how would you convert a rotary output from a motor to a strain gauge - would you have to have some sort of slipping clutch connected to a bending lever?

EDIT ***Gotta add something. To convert the rotary output you free up your loading motor and let the load cell take up the load that would have been taken by the full mounting.***

Nope, much more simple. That is the basic idea though, this is just a different method. Usually you find load cells in a watch battery kind of shape. What you do is attatch a lever to you loading motor, and the load cell to the end of the lever. You do this all in the direction so that when running everything is trying to compress the load cell. The load cell then outputs a voltage relative to the force that is applied to it. Do some math and you get torque, add rpm and more math and get power, add electrical measurements and get efficiency.

Let me know if you need more explanation, or a picture. Right now I'm trying to think of a way to show it as a pic, may just make a solid model.

Steve

[desertstalker]

You mean measure torque at stall?

That is not going to help a huge amount BLDC motors dont work properly at stall (not like a DC one). You would also kill ESCs all over the place.

[JKos]

No, not stall torque. Torque spinning under load. Like a dyno.

- John