Brushless Motor Comparison Testing

[questtek]

In an attempt to get some meaningful data on the performance (thus comparison) of brushless motors for FE’s, I am building an evaluation platform that I think may help provide some guidance on brushless motor selection. This goal of this evaluation platform it to be a bridge between Brushless Motor Manufacturer Published Specs, which I often refer to as Brushless Ultimate Linguistic Literature Showcasing Highly Improbable Technology , (BULLSHI* for short), and what we actually see after plunking our hard earned cash.

In a nutshell, here is the concept:

1. Use a 44” Aeromarine Avenger Pro hull at the test platform. It’s wide beam, high freeboard and large internal volume to hold a wide number of LiPo cells makes it the perfect test platform. Most importantly, I have one available. The boat will be in the water connected to the dock via two stainless eye bolts on the back of the Avenger and a stainless cable bolted to the Strain Gauge Force Transducer.
2. Design a universal, easy to change motor mounting system that will handle a wide range of motors from UL1 to Feigao 540’s and 580’s to the New and Castle Creation series and also the new Leopard series of 4074 and 5692 series of motors.
3. Any combination of ESC type, prop selection, and number of LiPo cells/voltage can all be easily selected as the specific test dictates.
4. Use a conventional flex drive that takes 3/16” shaft props and have a wide variety of couplers that connect this shaft to the motor. ( I hope to get Jeff Wolfe to help me on this one)
5. Do the testing attached to a dock in a lake to minimize the restrictions and errors associated with tank testing. (Also lucky enough to have one of these in the front of my house)
6. Instrument the motor/esc system with Eagle Tree monitoring to obtain all necessary performance parameters. (RPM, Amps, Voltage, 3 Temps, Watt-Hrs consumed, etc)
7. Include an Eagle Tree A/D expander module so the force output from a precision strain gauge transducer can measure thrust. (I considered using an inexpensive digital fish weighing gauge but that would neither be as accurate as the precision force transducer and would require an observer to monitor the force output by viewing the fish scale LCD, a big source of error in my opinion.) Preliminary tests on this force transducer show excellent results. I use a 9 VDC strain guage excitation voltage and a 3.7 volt amplification voltage. Maximum force (thrust) recorded is 50 lbs and I have a built in amplifier to provide a 0-5 VDC calibrated output to the Eagle Tree A/D conterter)
8. All data is fed directly into a Laptop where it is monitored via an active Eagle Tree software display page as well as stored in memory.
9. A standardized tabular and graphical form will be established to present the recorded data so an apple to apple, not a grape to watermelon comparison can be made.
10. Have Tony, Mark F, Jeff, Brad, Josh, etc monitor testing and provide suggestions as needed as well as look for constructive input from the FE forum.

Preliminary equipment setup shown in the attached Pics....Ideas and Suggestions?

[tth]

Curious to see some results.......

[questtek]

This is a "Works in Progress". I still have to build the universal mount and get all the hardware sorted. Tomorrow, a meeting with some of the FE guys will provide a bit more guidance and direction. Will keep you posted.

[Jeff Wohlt]

Whatever you need bud!

[m4a1usr]

You left out one of the most important components for accurately testing the items you seek to define. The power. What cells, how they are treated, where are they in their life cycle, is everything defined for connectivity? Unless your parameters are equally accurate for each sample, the resulting data for all intents and purpose is meaningless.

You got to put together an accurate test plan. Ensure it does not deviate from the plan due to conditions or encumbrances. Data must be recorded for not only the same time duration but equal enviornmental conditions as well. Variations contaminate your sampling.

I think I see where you are going but to those of us who test things for a living you have some serious issues to address. That is if you want to be taken seriously.

John

[Jeff Wohlt]

Knowing what he does and plays with for a living, I will believe what he ends up with will be well worth looking at. I think we all know the rules when getting data....must be VERY accurate and ALL conditions equal. All we can do is make sure cells are at same peak condition, water conditions, water temps can also play a role and winds. All else remains the same...props, cg, etc.

If he can get those that close, as I am sure he will, then I think we are go for good testing. I think you will see which motors test better. Maybe a better way is a dyno out of the water that can measure it all and apply resistance equally at the shaft...but this is not real world we use.

But I do know what you are saying, John.

[m4a1usr]

Knowing what he does and plays with for a living, I will believe what he ends up with will be well worth looking at. I think we all know the rules when getting data....must be VERY accurate and ALL conditions equal. All we can do is make sure cells are at same peak condition, water conditions, water temps can also play a role and winds. All else remains the same...props, cg, etc.

If he can get those that close, as I am sure he will, then I think we are go for good testing. I think you will see which motors test better. Maybe a better way is a dyno out of the water that can measure it all and apply resistance equally at the shaft...but this is not real world we use.

But I do know what you are saying, John.

Doing what Joe is seeking is probably the best demonstrable effort I have seen in our hobby. Just to know someone is wanting to define performance characteristics speaks volumes. And I certainly dont want to rain on this effort but data sampling contamination is what constitutes margin of error. Creates doubt. I for one would like to see uniformity and consistency. I know he has the knowledge and experience.

I used to run a dyno facility back in the late 90's. That would be the best option if available. But that cost big bux. Best advice is go forward and let the results speak for themselves. Using calibrated equipment and proven documented procedures provides the best results.

I am confident you guys have everyones interests at heart.

John

[properchopper]

You left out one of the most important components for accurately testing the items you seek to define. The power. What cells, how they are treated, where are they in their life cycle, is everything defined for connectivity? Unless your parameters are equally accurate for each sample, the resulting data for all intents and purpose is meaningless.

You got to put together an accurate test plan. Ensure it does not deviate from the plan due to conditions or encumbrances. Data must be recorded for not only the same time duration but equal enviornmental conditions as well. Variations contaminate your sampling.

I think I see where you are going but to those of us who test things for a living you have some serious issues to address. That is if you want to be taken seriously.

John

Whoa Nellie ! John is absolutely right. To derive uncontaminated data the independant variables, especially the power source, must be completely standardized to come up with meaningfull dependant variable data. Using lipos as a standardized source of power won't provide this standardization; I'm sure we've all experienced the variation in lipo power on various days when the lipos were happy and when they seem to be sluggish without any real explanation -
[ see my article in the Journal of Fast Electric Tomfoolery - "Moody Lipos-Fact or Fiction" - P. Chopper 2009]

We'll need something like this feeding the experimental test bed - I'll bring it tomorrow ! [grunt!]

[questtek]

Geat, this is exactly the type of suggestions I was looking for. Keep the ideas and comments coming! Since this is at a dock, I have access to AC power and also have a large 6 battery bank of heavy duty marine batteries in my electric boat. Since the Eagle Tree data also records continuous battery pac voltage this should also give a reference for comparison since many parameters examined per volt input. Tony, I cannot wait to see your device tomorrow.

[Simon.O.]

This looks like a very interesting project and should yeild some good results.
I am a bit of a numbers type at times and I like data to work with, especially feild proven data.

The is one thing that is glaringly obvious here. All the tests are conducted in the same way, so far so good.

Will the prop be submerged or able to be raised a bit, to "surface drive" or am I missing something here.

I do like the idea

[sailr]

I have to totally agree with PropperChopper. He beat me to it. I was going to suggest a big power supply onshore that could be connected through the hatch of the boat (watertight) with a flexcable.

I certainly applaud your efforts. Several years ago I made a line of brushless airplane motors. I hired a guy to design a test setup that determined the amps, thrust, etc. for each motor on several different props, volts, etc. The results were impressive. In that case of course we used airplane propellers.

Boat motor data is much more daunting to obtain but it should certainly be a good benchmark from which to start!

Thank you for your efforts!

Geat, this is exactly the type of suggestions I was looking for. Keep the ideas and comments coming! Since this is at a dock, I have access to AC power and also have a large 6 battery bank of heavy duty marine batteries in my electric boat. Since the Eagle Tree data also records continuous battery pac voltage this should also give a reference for comparison since many parameters examined per volt input. Tony, I cannot wait to see your device tomorrow.

[sailr]

Good question about the depth of the prop in the water. We all know that can make an incredible difference in the amp draw, etc.

One more thing. Since the boat will not be moving through the water, you probably will not have sufficient cooling of the esc and motor. You will want to consider a pump in the boat to ensure sufficient circulation.

One last thing I see, and I don't have a clue how to do it, is to obtain, devise, etc. an industrial strength speed controller. I'd hate to see you frequently letting the smoke out!

This looks like a very interesting project and should yeild some good results.
I am a bit of a numbers type at times and I like data to work with, especially feild proven data.

The is one thing that is glaringly obvious here. All the tests are conducted in the same way, so far so good.

Will the prop be submerged or able to be raised a bit, to "surface drive" or am I missing something here.

I do like the idea

[Jeff Wohlt]

Good stuff! Joe, if you need couplers or anything just drop me a note. N/C since it is for the good of all of us.

[questtek]

Good question about the depth of the prop in the water. We all know that can make an incredible difference in the amp draw, etc.

One more thing. Since the boat will not be moving through the water, you probably will not have sufficient cooling of the esc and motor. You will want to consider a pump in the boat to ensure sufficient circulation.

One last thing I see, and I don't have a clue how to do it, is to obtain, devise, etc. an industrial strength speed controller. I'd hate to see you frequently letting the smoke out!

All very good points. The prop will be totally submerged and the depth controlled by adding an 6 lb block or lead (dive weight) into the aft of the hull inside. The prop will then be totally submerged. As motor weight varies in testing, this weight can be increased or decreased to reasonably maintain a uniform depth.

For cooling Jeff Wolft and I are big advocates of fan and forced water cooling. I have some 12 vdc micropumps perfectly suited to the job. You can see some pics on a recent post regarding ESC cooling.

I am using inexpensive 200A mystery controllers. I have about 5 or 5 of them to play with and probably expect to blow a few of them but they are not that expensive. I have found that with proper pumped water and fan cooling they perfom pretty well. I mount temp sensors on the FETS and the caps and keep track of how they are "cooking" with the Eagle Tree.

Tony brought down his big power supply. It is limited to 50 amp draw. For high draw I have 6 giant marine deep cycle batteries I can use.

However, prior to in water testing I thought I would play around with some bench dyno testing first. My next post provides some details.

[questtek]

I built a simple dyno test stand to help me evaluate some of the new brushless motors. The "DYNO" part is a very large 5000-6000 watt brushless motor. It is driven via a coupler to the motor being tested. "DYNO" output is an AC voltage. This can be easily measured and matched up with the tested motor data that is monitored by an EagleTree system. I posted a short video of this set up:

http://www.youtube.com/watch?v=1thlLKZ5_c8&feature=youtube_gdata