3<->8 kW motor comparsion

Finally i've got this MONSTER!
3kW - same motor as Cromotor, my own edition. And this 8kw motor..
Pictures to attract attention:






Weight 20.5kg
W nom 8kW
W peak ~20kW
Dropout 14mm
Sadly, but this monster doesn't fit on my bicycle
Any questions/suggestions? Huh

Can you please measure the phase resistance and no-load current at nominal voltage.
Phase resistance is accurately measured by applying an constant current of 1 amps through one phase at the time.
Then measure the millivolts across the phase input connectors using a good multimeter.
Each millivolt measured = 1 milliohm copper winding resistance.

E'g apply 1amp precisely (must be measured by series current meter) and if you then measure 12mV it equals 12 mR phase resistance.
Be sure to measure directly on the phase connector termination and not the connector applying the test amps.
There can be several milliohms in contact resistance and that will give you a false reading.

I suspect the internal construction is similar to the Cromotor (which was well-researched, and upgraded in the V3 version). If you pull it apart, please take pictures. A frequent question is the width and diameter of the stator, and the thickness of the individual laminations (0.50mm and 0.30mm seem to be common). If you count the number of laminations, you can just divide the total width by the quantity in order to discern the lam thickness.

Thanks for posting this.

edit: Russian website with an address on their North-East coast in their port city of Vladivostok: http://eco-logics.org/3-motory

Jesus.... 44 lb wheel... That thing makes the cromotor look like a baby. Can't wait to see it in action, but I think we're approaching the limit of unsprung rotating mass at this point... 8)

P.S. hahahahaha. 250w.....

A bit later will try to disassemble it.
Spoke diameter 305mm
Dropout almost 200mm
Magnets same as cromo - 50mm

Here i got one test sheet:


I don't know phase current for this test, but i think it can get more Nm for this motor

18 bolts on 1 side cover, must be a beast! Phase wire Gauge?

phase wires 16mm²

3 posts hu? Are you selling this motor?
I wonder how long the axel will take all that torque?

I'm russian, you can find more messages on http://electrotransport.ru/ussr/index.php?action=profile;area=showposts;u=17813
This is not first time i visit this forum. Just mentioned not good quality video in thread "Cromotor mammoth" and decided to show the photos of real Mammoth (with a big 'M')
Not selling it, at least till i will be sure there is no any way to connect it to my bicycle.

Axle 18mm diameter, so why not? it is 14mm dropout hole. If you make clamping dropout it would not be a big problem
Stator photo from manufacturer:

Sorry, i forgot my tools at work, have nothing to disassemble
Looks like a high torque motor, huh?

That will be madness in a bicycle!

11 days ago I would have called this an April fools joke.... 8)

Just wow

Vasalisk said

but i think it can get more Nm for this motor

Click to expand...

I think you are right!
63 stator teeth. It looks very similar to a version 3 cro manufacturing style, only really big diameter.
Thanks for sharing, have fun with this heavy beast.
Zappy

zappy, that's coz it is same manufacturer (QS motor)
you can see white sticker on greyborg home page head, on the motor - this was QS sticker. Looks like they usin good glue

Just let me know when you're ready for a race. 8)

8kw? great for a motorcycle. Death wish on an ebike!

As i promised, inside photo









56 magnet
63 tooth

Looks like the magic pie has been taking steroids.



Magic pie stator for comparison.

I bet that motor has an excellent sound due to it's high pole count

VasiliSk said:

A bit later will try to disassemble it.
Spoke diameter 305mm
Dropout almost 200mm
Magnets same as cromo - 50mm

Here i got one test sheet:

I don't know phase current for this test, but i think it can get more Nm for this motor

Click to expand...

Those numbers are not even close to the dyno sheet for the Mammoth motor that Zelina Vozila sent to me.

Looking at the 3rd row Max power out you see
Vin = 69
Ain = 143
Win in 9906
Torque 133 Nm
RPM = 537
Power Out 7492W
Efficency 77%

My dyno sheet has the following for similar Volt/ amps
Vin = 64
Ain = 149
Win in 9586
Torque 70 Nm
RPM = 1125
Power Out 8198W
Efficency 86%

As you can see they are 2 very different motors. They may share the same stator core (I won't know until I get my unit and open it up and take pictures) and lamination pattern but the number of turns per tooth (KV aka rpm/volt of the motor) and the over all quality of the motors are different. From what I know Zelena Vozila chooses the motor parts for the builds to increase the overall quality vs an off the shelf setup with their motors. There is a very large difference in the efficiency of the motor chart you posted vs what I have.

The peak output (not input) of the dyno sheet I have show the motor outputting well over 11,000W@ 84% efficiency, 800 rpms and the supply votlage dropped all thay to 55V.

I can't post the dyno plot without permission, but what you posted vs the specs I have are 2 VERY different motors.

If you have any dyno information for the motor you think is the same as the Cromotor it would be nice to see. The Cromotor is > 90% efficiency.

I'm not saying what you posted are bad motors, could be a good deal if you build custom swing arms. I'm just letting you and others know that you can't tell two motors are the same by just looking at pictures. The quality of the internals and their specs plays a large role and Zelena Vozila is active in this vs just getting a lower cost common off the shelf motor. Please do not say it is the same internally and mislead people.

Same - i mean only 3kW motor. Cromotor. Internally they are different winding, i have more options
Thanks for info!

That smaller motor looks similar to a cromotor but with lower efficiency. Its closer to what the v0 and v1 motors. Materials make all the difference, but higher quality will cost you more and have a higher moq, probably over 100 motors since it needs to be customized.

what material you are talking about? stator steel? winding configuration?

Also as i can say from my experience, motors with lower RPM & more torque less effective than higher RPM & less torque. Also high RPM less weight motors. They are totally different, your Dyno and this 8kW hub

VasiliSk said:

what material you are talking about? stator steel? winding configuration?

Click to expand...

Copper fill is copper fill so not much can be changed much there. The type and thickness of the stator laminations plays a large role in motor performance. Then there are several types of magnets, some are better than others, different temp ratings, strength.

Many motors look the same internally but perform differently. The other issue is custom machine work to fit them into a standard size drop out. If you do get custom motors made you should read some of my posts about manufacturing issues that we have encountered with the Cromotors. I have posted about many of the delays on this forum that were caused by the manufacturer and then Zelena Vozila had to fix them themselves.

Doing small custom orders with Chinese manufacturers can be tricky at best and disastrous at worst. Even large reputable companies. I did a lot of research on it and was shocked by some of the stories companies ordering small quantities of motors <500 units being small, had told me. It scared me away from dealt directly with the usual suspects. Now that I resell these motors to shops that deal with EVs I have heard even more.

Right now I am waiting on a. Chinese manufacturer to deliver 100units of throttle tamers I had them make. They are behind schedule and its annoying, but in the grand scheme of orders I am nothing so I have no leverage to motivate them.

Already get known what is chinese manufacturers. Hopefully problem was fixed on time, and couse only 2 week delay
I know, here is a lot of work in future for this motor. I need to make new melting form for cover and other things, to make it more "user-friendly".
Here is only 200km from a chinese border. That make sense.

zombiess said:

The Cromotor is > 90% efficiency.

Click to expand...

Where is your evidence?
There is no data shows any version of cromotor have efficiency more than 87% !
If you have such data please share or do not tell anybody the numbers you cannot proof

zombiess said:

Looking at the 3rd row Max power out you see
Vin = 69
Ain = 143
Win in 9906
Torque 133 Nm
RPM = 537
Power Out 7492W
Efficency 77%

My dyno sheet has the following for similar Volt/ amps
Vin = 64
Ain = 149
Win in 9586
Torque 70 Nm
RPM = 1125
Power Out 8198W
Efficency 86%
As you can see they are 2 very different motors.

Click to expand...

You cannot compare motor power at different RPM, If you look closely at the numbers, there is almost 2x difference in TORQUE

So to make an honest comparation, you need to compare the motors with equal Kv at least, not mentioning they should be tested with the same controller on the same dyno ...