Motor Power/RPM Tests
 

Here are the RPM tests I've been promising, along with an updated Power Usage test. Keep in mind these are just the motors that I have...I don't own a store (that's Tiny's gig) so if you don't see a motor tested here it's because I don't have it.

Motors tested
Tomy: 1.0, 1.6, 2.2 and 2.6
ZipZaps: Stock, Performance, Turbo, and Racing
Bit Char-gmotors: 2.6, 3.0, 3.2 and 3.8
TinyRC: 3.8, R-spec and Formula34

Testing environment
For the RPM tests:
I used a Tachometer that Wild03 (Forum Member) made. All props and credit for that belongs to him. you can build one as well, check out his site:
http://www.geocities.com/wdiaz03/tachcometer.html

Instead of putting the mouse encoder wheel (from the site above) directly on the Motor...I took apart a 12:1 Axle and attached the encoder to the Axle. The reason for doing this was because my first batch of tests had erroneous results at higher than 22,000rpm. Using the axle with the 12:1 gearing brings down the initial readings and results in better numbers.

Once mounted to the car, the car was charged to full, run for a short time and then the tests were done at ~1.34v

For the Power Usage tests:
The Motors were mounted in a clip from a work badge (looks like a big alligator clip) with a ground wire run through touching the barrel when mounted. To provide the power, the ground wire was run to one side of a battery (a fully charged, 160mAH NiMH Bit battery) and the negative was run through my Digital Multimeter (in series, to get readings) and then to the metal piece on the motor endbell to close the circuit and get the motor running.

In previous tests the PCB was in the middle and any limitation of the PCB would taint the results. This time the tests are done straight from the power source.

I tested for no load against the motor and 'stalled' (the motor shaft was forcefully held not to spin).



Results:

All results (in the Power Usage tests) are in MilliAmps (mA)

http://tinyrc.com/lincoln/Images/Mis...MotorTests.gif

* Indicates I had more than 1 of that Motor and the number listed is the average of all the tests for those motors.


Final Thoughts
In the RPM department, for the most part the motors perform to what they're rated. The higher RPM motors come in a little under their rating though, but not by much.

As far as the Current usage tests, there's 2 things these numbers tell you; motor efficiency (runtime) and how much juice it'll demand to spin the wheels.

The numbers under no load gives you an idea of the effiency of the Motor, the lower the number the less power it demands and therefore longer runtimes. Take the Tomy 2.2 vs the 2.6, even though the 2.6 is a higher RPM motor it uses less power when running and will last considerably longer than the 2.2!

The stalled numbers (I believe, not positive on this yet) indicates how much the motor will demand for power to spin the wheels. The higher the number, the more "pull" it has...I'll have more concrete info when I do the 'hill climb' tests. I'm especially interested in that Bit Char-Gmotor 3.0, at no load it's pulling A LOT of juice!

My next batch of tests will be to see how steep an incline the motors can handle, this will compliment the power usage tests and give us a better picture of Torque.

would it be possible to do this somehow but with the same load the car puts on it? so we can get a better understanding bcuz the rpm with no load doesn tell us enough

Cool. Let me be the first to say thanks for the effort!

Thank you! good stuff you got there. Makes me think...i wonder if there is a good way to measure the torque? I'm thinking like one of them stationary bikes, turn up the levels of resistance till the motor can't turn anymore...:D

anyways, thats really cool!

EDIT: hehehehe i just re-read your post and saw the part about torque...man am i dumb or what? :D

Audi-TT,
Yes, it would be great to do such tests...But that would probably require building a dynamometer (and all that would entail) to test these little 'toys', well I just don't know if I'm THAT crazy yet.

While the RPM with no load alone doesn't give you much...You CAN match it up with my other tests (like the battery tests and the Motor Power Usage tests) and all together some things about the motors start to show.

cool info man, thanx a lot

does the power usage when it is stalled have anythjing to do with how much the torque the motor would have? im just wondering

thanx again

Nice work!
 

Thanks for the info! You should move your own thread to Bit Science!

It is my belief that the stalled current indicates how much juice the motor demands before giving up...So in essence yes, I think that equates to torque.

I'll be more sure when I do the incline tests.

Any chance of including bitmod1 3.0, 3.2, 3.5 motors?
How about Perfection 3.0, 3.8?
DKS rotors, etc.?
It'd be great to have a complete table of the most popular motors.

Any news about that micro-b dyno thing, perhaps for some real torque numbers?

Excellent work so far. Looking forward to incline tests.

I've merged the Power Usage and RPM test threads. So if things seem a little out of place, that's way.

Figured this is the best way to keep everything together.

actofgod,

I will try contacting the retailers for those motors and see if they want to send me any motors to test.

As usual us aussies are just too good!
 

DYNO project.

Used it on the weekend, check it here.

http://www.ausmicro.com/link.asp?TOPIC_ID=527

ph2t.

maybe you could test a dual and tri cell setup to prove whether a motor's speed is doubled and tripled by double and tripling the voltage. if the law of diminishing returns apply here, then it'll quiet those people who say their tri cell 3.0 runs at 9.0 or something along those lines

can you try that with a perfection 3.8
and compaire

he can only test what he has so if u want him to test the perfection 3.8, u betta donate one to him then :D