Calling All Brainiacs!

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.

[Procharged5.0]

[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".

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.

[Procharged5.0]

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.

[Procharged5.0]

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.

[Procharged5.0]

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

Forgive me for trying to help you make something useful.

[Procharged5.0]

Originally Posted by Bomb-Proof

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.

[BrianG]

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...

[Procharged5.0]

Thanks Brian. All good points.

[GriffinRU]

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)

[Serum]

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..

[Procharged5.0]

Originally Posted by Serum

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.