Calling All Brainiacs!
 

I think we should develope a brushless motor dyno. Something that can handle a minimum of 2250w (3+ HP). Something to test torque, efficiency, RPM/v (loaded & unloaded, etc), current draw. etc.).

Maybe it's possible to utilize existing software or even base it off of a Eagletree.

Load can be provided by eddy current power absorber or a water brake absorber.

Any interest or thoughts????? I have ideas and some sources for hardware & software but not the time to pull it all together.

I have been trying to come up with something as well. Software is the biggest part of it, but not a roadblock by any means. I have an idea of how to do it, but I need to do alot of math to get it correct.

I know of one or two companies that customize their software and have an excellent product. Cost becomes the issue there.

The other issue is a variable power supply for the motor. What's needed? 50V @ 150A? It should be a supply vs battery but how big would it need to be assuming it's a quality supply with adequate "headroom"????

you would use a the battery you will be running with the motor, and the ESC. No need for a powersupply like a brushed motor.

What you need..
Steel drum balanced w/accurate weight
A way to spin it by the motor (simple chain drive is easiest)
RPM sensor on drum/shaft
Software to translate the data

Companies offer the software w/sensors...around $1K.

Should aim higher on watts, My 7XL and 9XL on 5s will pull 1900 watts peak, and i know there are stronger motors out there. People like Promod, CHC, Aquwt and the Bomb-proof guys are eclipsing that easy right now. all you need is an eagletree and a calculator for real world figures, but it would be cool to see max loaded numbers. BTW how many watts is there to 1 HP? I have heard its somewhere between 740 to 750 but never have heard a definate number

745.7watts=1Hp

thanks

I agree. Aim Higher. There are many out there surpassing those numbers now. Crazy, The eagletree will give you real world INPUT power nummbers, but not output numbers.

I saw a video somewhere around here of a nitro motor dyno, all you would need is an adapter to mount an electric motor in it and it should do the job. The dyno doesnt know what is generating the power, it just measures the power being generated. Putting an eagle tree on the input side would give you a comparision of input power to output power and allow you to measure overall system efficency. That would be really cool.

I would love to see something like this come together any way that it can happen. Its just that kind of tool that will tell how much better the high end motors are than the less expensive versions. I suspect it will be an EXPENSIVE project though.

Yes, it could be expensive. I have a number of potential ideas and concepts right now on this. One of them might just work out.

Keep the ideas coming guys........

BTW, Bomb_proof the power supply would be the only way (well maybe not the only way) to keep repeatable voltage and current numbers for DYNO accuracy. Batteries would not provide the consistency. Now potentially several car or marine batteries in series could but then there would be no way to control the voltage supply to the esc. You would be stuck whatever the battery voltage was.

It would be great to have the supply to mimic the voltage of the cells being used. 3s, 4s, 5s, 6s, etc.

Yeah, I didn't think before posting, you're right i'm pulling 1900watts peak out of the batteries. It would be good to see real world efficiency numbers, not the ones that the manufacturer puts up

Perhaps aiming for 3000 watts would be the starting point and hopefully higher if it's possible. That would give us a 4HP capacity. More than a 540 based motor is likely to produce.

Using quality batteries for powersupply is best method, and real world results. A perfect power supply will fluff the numbers and make them higher.

My concern is about consistency. batteries vary batch to batch, brand to brand, and by number of cycles.

I think you'd want to do both methods. Components should be compared under controlled conditions.

If you want a good reference, you woul need a killer controller to start with.. only controller i know that is capable of pushing i that far is the kontronic 63V. it´s not impossible to do though, but i don´t see it happen..

The constant voltage test can be calculated on paper, the only thing a dyno run would do is confirm the motor is in spec. On a true battery source, you would get useful info and real world #s. Batteries vary, but you need a random lipo pack to do the testing, and use same pack for every motor that uses that voltage range. Lipo packs are build to pretty strict specs and wont vary near as much as a Nicd or Nimh, so I dont ever expect to see a "matched" lipo pack for sale.

[quote=Bomb-Proof]the only thing a dyno run would do is confirm the motor is in spec.quote]

Not true.

First of all, not all motors are tested using the same standards. The Feigao motors are given their Kv rating "unloaded" whereas the NUE, Lehner, and others are given their Kv rating "loaded".

A dyno could be configured to provide useful "torque under load" info and "current draw under load".

Correct, but you can calculate that info loaded and unloaded. You dont need a dyno for that. They will vary from real results slightly due to impurity in materials and build technique. They are close enough that some manufactures use these specs. These companies know these #s way before the motor is even built.

I didnt say it was easy, but its useless info IMO. Its like testing a full scale engine on a dyno with freezing air in the dyno room...makes great #s, but isnt real world.

For sake of comparing one motor or wind to another, a dyno would be of value. Subtle, or not the differences would be seen and could then be compared. Comparing efficiency, heat and other data would also be a benefit.

I agree that most info can be calculated but some info can not.

Yea, but persoanlly I wanna see real #s instead of perfect #s. The perfect #s would be good for quick referance though.

Sorry BP. I've spent some time in/on 1:1 dyno's. They do not give a 100% replication of the real world. But they absolutely and unequivocally give you a bench mark on performance and help you to compare performance changes. IE: Dyno the motor. Change the headers. Dyno the motor. review the gains/losses/power curve, etc. The same holds true with electric motors. I know that it won't tell you the whole story but it WILL tell you something about the motor's power generating characteristics, efficiency, etc. It WILL generate valuable info to be used IN CONJUNCTION with field testing.

I have as well. And the air temperature can vary the HP readings 100hp in some cases. You get as close to actual parameters as you can, or you are just fooling yourself. Why have a result of 3hp at 20v constant when no battery can do said load and hold 20v? (random #s) It would be useless info as far as real world power. It could be used to compare different motors, but one motor would pull the voltage down more than another in the reak world, thus altering the #s greatly in some cases.

I'm done. Dyno's are useless. Bomb-Proof Has Spoken.

Forgive me for trying to help you make something useful.

All due respect BP, all I see is you disagreeing with all my points, even after I've acknowledged your valuable / valid points.

How is that helpful?

Simply put,

Dyno's exist because they provide useful info. PERIOD. They are not the answer to everything and will not solve the world's problems. I know this. But they provide useful info.

Batteries could be used as a power supply. We could do that. Pre-programmed "throttle pulse profiles" could be programmed in and if the motor is under load (or if we built a RC chassis dyno) would give closer to real world performance estimates.

I tend to agree. Dynos won't be 100% accurate because there are other factors in a real system, but at least you can compare the numbers to see the relative performace difference with BL vs Nitro, or setup changes.

As far as the power supply used; I'd just use a typical power source found in a typical setup; lipos or NiMH cells. I wouldn't use a power supply without taking other precautions because the back EMF can damage the regulator circuits unless measures are taken. Other than that, a power supply could be a good idea providing it had similar load characteristics as a good set of batteries. Meaning: it should NOT be tightly regulated. You want the output voltage to fall somewhat with high loads to simulate a typical battery setup. This could be easily done with a linear regulator circuit with loose regulation. Losses would be kinda high, but we aren't concerned about efficiency here.

Just my $0.02...

Thanks Brian. All good points.

With eagletree and similar products building a dyno is fun but only if at the end you plan to put sticker on BL motor with power ratings.

Math and software is simple, even electronics are not that bad. Spinning motor shafts at high RPM with high torque is the problem.

You can use 2 motors one as load and another as test. Monitoring shaft load with torque sensor, temperature and phase current and voltage on both motors plus encoders to monitor RPM will allow you to plot DYNO data. Data acquisition system must be at least mid-to-high end.

Or you can spin a drum, and only use data from one motor...

Artur

P.S.
For power use 1-3 12V Car batteries (cheap and easy)

I personally don't see the use of a dyno to proof how fast your ride CAN be..

A dyno doesn't give an insight in how hot your setup runs, changing the gearing (load) etc.

I personally don't need a dyno or the information a dyno puts out.

One thing that i am curious about; what makes a 1:1 dyno vary a 100hp? is it the motor that benefits from the cold air?

Please use this forum to share information, not to brag with knowledge or attitude.

Why dyno's are used on 1:1 vehicles? to show you if you are heading the right way with tuning an engine.. Or to give you information you can brag about on birthday parties..

That's a question that almost requires a llengthy answer.

However in the interest of time:

Air density has a HUGE effect on power production in an internal combustion engine.

Cold dry air allows for more fuel and for greater "packing" of the cylinders, thus more power production. In a sense an engine is an "air pump". An oversimplification but still true.

The more power an engine makes the more of a gain or loss can be seen when atmospheric conditions change.

Dyano's can be useful in many, many, ways. For 1:1 you can load the motor down (Dynojet 248x, Mustang Dyno, etc.) and seee how the motor/car performs under load. The tests can be run steady state or dynamically.

Dyno tests for RC motors can be run (if set up properly) to determine the heat buildup in the motor & esc.

The tests vcould determine the "power curve" of a motor, the total output of the motor (loaded & unloaded) among other things which would tell you that your Lehner 1950/7 makes 11% more power with 2% greater effenciency and 20 degrees lees ESC heat than a Feigao 7XL for example. What you choose to do with the infor after that is up to you.

It might also be noticed that one motor has a better "midrange" power and/or efficience than another motor making it a better choice for certain racing apps.

just food for thought.

LOL Procharged thats the funniest photo ever...you've just made my day... rofl...

If you want proper temperature readings, an easy way to get consistent results is to isolate the motor (possibly with the load creator as well) and then monitor changes of the ambient temperature in the isolated box, or container, or whatever. You will probably need a fan to expedite the transfer of heat to air, and would also need to ensure that other things in the box generate minimal amounts of heat. Then, you can just measure the change in temperature.

As for the load creator, I think a great idea would be a prop in water. However, most importantly, you must find a way to make sure NO air gets inside the water and near the prop, as it will change the overall density of the water in that area and lighten the load, producing varying readings.

You may also want to make some sort of way of preventing different gearing from affecting results.

Please explain...........

Is this a comment in general or are you accusing me of something?

I thought I addressed the topic from the standpoint of sharing info and brainstorming with "the collective" here in the forums. If you feel differently I'd like to know.

I don't feel like I show attitude or brag. Although I'll admit to getting impatient with a certain forum member.

If you feel differently I'd like to know.

For loading, I think another BL motor would work. Just short the phases and let motor braking set the load.

That would provide a compact and consistant load. Good idea Brian. I like it.

Not sure if this has come up already, but a huge aspect of performance in brushless is the batteries.

Having dyno charts of all the different motors would be great. But there would need to be a lot of data to translate to predict actual performance. A motor would need to be tested under a wide range of voltages and loads.

Then a guy would need to know what his batteries can do... voltage drop under load... to match the right dyno chart.

But.... any dyno tests are welcomed if someone gets it done!!

IF a dyno were built it would be cool to offer a dyno service. Send your packs(s), motor(S), charging ritual, etc to the test cell and have it dyno'd. Then you get back information specific to your combo.

An RC chassis dyno is also fascination to consider. having the combo tested in your car but "within the lab".

BTW...

I just acquired an Eagletree systems data recorder..............

You got mail Hank.

i think that explains.

it was directed to a certain other member.

Good to know.

Thanks Rene!

Anytime Hank.