The Unofficial 'CroMotor' Owners Tech-Tips Thread

[chroot]

I have a question, I see this cromotor has 3 turn seems too fast with no torque at all since Doctorbass says it equal to xlyte 5302. I am going build a race ebike and trail ebike. The trail ebike would need some torque for climbing the hills or mountain's trail.

Let me know

 

[gensem]

I have a question, I see this cromotor has 3 turn seems too fast with no torque at all since Doctorbass says it equal to xlyte 5302. I am going build a race ebike and trail ebike. The trail ebike would need some torque for climbing the hills or mountain's trail.

Let me know

there is no such of thing as a motor with no torque... what wheel size are you planning to use?
btw i think it would be better to wait for some real world tests, they are bound to happen soon.

 

[John in CR]

It will have lots of torque per amp. It has a Kv of just under 10rpm/V, so nothing like a X5303 or X5302. My motor with a 50mm stator (though larger diameter) seems to alternate between 1 and 2 turns, or maybe it's 1.5 turns...hard to tell. Mine has a Kv of about 16/v and plenty of torque, since meant for a 300lb scooter. There's definitely no worries about torque, so ignore comparisons to Xlyte motors that are invalid.

 

[chroot]

I am going use 20" wheel with pirelli motorcycle tires.

I have a question, I see this cromotor has 3 turn seems too fast with no torque at all since Doctorbass says it equal to xlyte 5302. I am going build a race ebike and trail ebike. The trail ebike would need some torque for climbing the hills or mountain's trail.

Let me know

there is no such of thing as a motor with no torque... what wheel size are you planning to use?
btw i think it would be better to wait for some real world tests, they are bound to happen soon.

 

[chroot]

OK you says so, Can you give me estimate how fast at 66v-20Ah LiPo (18s4p). Will it able climb up the mountain trails or hilly trails.

It will have lots of torque per amp. It has a Kv of just under 10rpm/V, so nothing like a X5303 or X5302. My motor with a 50mm stator (though larger diameter) seems to alternate between 1 and 2 turns, or maybe it's 1.5 turns...hard to tell. Mine has a Kv of about 16/v and plenty of torque, since meant for a 300lb scooter. There's definitely no worries about torque, so ignore comparisons to Xlyte motors that are invalid.

 

[gensem]

I dont think a 17kv motor ll have "no torque" in a 20" wheel, even tho its not going to be a climber if you cant keep it on the best spot.
I dont have factual data too, but 12 were sold (9.5kv ones)and John Holmes is lacing a couple of motors so they are going to pop really soon.
Why dont you a try a 9.5kv one with 24s instead of 18s? Its going to be easier to keep in the 80% area and still have a good top speed.

regards

 

[sn0wchyld]

can someone give a comparison of kv/rpm to a currently known motor? ie in a 24" rim with 100v what would be an aprox. top speed? ive heard about 1km/h per v on a 26 but I may be confusing it with a different motor

 

[John in CR]

My 16Kv motors in a 20" wheel with a 40mm stator vs the 50mm on this one, but otherwise close to identical will do right at 60mph on the highway with voltage sagging to 76V or so on 20s. That's with 250lb me and 125lb bike though it is closer to a feet forward semi-recumbent than an upright. That's running 75A though 100A makes little difference on top end in a 20". Same motor in a 23.5" with LFP at 220lb and an 80lb bike running 110-120A nudged above 60mph, though that motor did run fairly hot on a long 7% grade. My daily rider above has done very long 8% grades doing about 35mph into a stiff headwind without heat issues.

Note that mine are appear to be 2 turn motors with the same pole and slot count as the CroMotor, and they're very hard on controllers. The 3 turn CroMotor, should have significantly higher inductance and be easier to drive, though that does remain to be seen. I haven't connected a controller to mine that will push it to hold on tight type torque, so they're very well behaved and quite "zippy" with great passing power even pushing only 75A. I did have to be careful of flipping with one setup, which was with a 19" wheel 100A and a quite small dual suspension bike.

My suggestion would be the 17Kv model with a 14" motorcycle rim giving you leeway of 19" to 21" wheel depending on the tire profile. Some of the 16" moto tires come in right around 20" too if you want a thinner tire. I have a 16" Pirelli and moto rim like that, and just need to get around to ordering spokes for it. Unless you want to spend the big bucks on a controller to go to higher voltages, the 17Kv model is capable of higher power with a 100V limit with plenty of speed and torque. The lower Kv model would be for those insisting on a 26" wheel, or those who need to tackle miles long grades of 10% or greater. For racing I'd opt for the higher Kv motor in the smallest wheel I could fit, since the higher rpm will cool better and the lower gearing is needed.

 

[dogman dan]

Gensem, it gets real complicated and half the time I have something ass backwards in my discussions so John has to dope slap me again.

But the general idea is to either use lower speed windings, or increase motor rpm with smaller diameter rims to increase the motors ability to climb a hill without excessive overheating.

Looks like this motor will have the mass to heat up a bit slower, So it might be real good on hills provided the trail surface and your riding ability allows you to keep the motor from going into the stalling condition. One of the main reasons I've become a huge fan of the slow motor approach is that I really don't prefer to get tossed over the bars into rocks and cactus any faster than 15 mph. So for my trails, slow motors and much less power works fine. It just depends on the purpose you have in mind, your comfortable riding speed, the type of trail you ride.

For many though, this will be a really nice motor for hauling ass around trails and roads where 40 mph speeds ( or much more) are no problem. But it wouldn't be the winding choice for slower crawling up extreme steep hills. It would, with plenty of watts supplied and a small rim, be quite a " you know this bike is dangerous right?" shoe throwing hill climber. You'd just have to be rider enough to hang onto it.

 

[gensem]

This is going to be my first powerfull motor and im going to tell you I think the 9.5kv is a good thing for thoses (like me) that dont want to run a 16" tire with a 17kv motor and put down 20kw of power aside the fact that it will probably do 24s lipo without smoking controllers.
Getting parts and machinery down here is hard and quite pricy so Im better off using 24/26" wheels aside the fact that I want to look like a bicycle. So let the 17kv hub for the crazy folks.

 

[John in CR]

Is this really a different winding, or is it just WYE vs Delta? Is the difference in Kv just a coincidence? If so, then the slower terminated motor is likely to have a slightly lower max efficiency. At least that's what the motor test report showed for the one Delta/WYE switchable motor I know of.

John

 

[gensem]

Is this really a different winding, or is it just WYE vs Delta? Is the difference in Kv just a coincidence? If so, then the slower terminated motor is likely to have a slightly lower max efficiency. At least that's what the motor test report showed for the one Delta/WYE switchable motor I know of.

John

Not sure John, the number fits the Wye/Delta bill but i think its a diferent turn count, otherwise there would be no need to wait for the 17kv "manufactoring" wich has a lead time of 2 months.
Accountant should be able to tell us for sure.

 

[fractal]

Hi guys, I found these specs on the official Greyborg thread. It was tested on 48 volts. They were posted by Markobetti, one of the developpers of the motor. Can anyone elaborate on this data? I have very limited knowledge on data like this and would like to learn. Thanks!

 

[zombiess]

Hi guys, I found these specs on the official Greyborg thread. It was tested on 48 volts. They were posted by Markobetti, one of the developpers of the motor. Can anyone elaborate on this data? I have very limited knowledge on data like this and would like to learn. Thanks!

I used this chart and played with the ebikecalc17 program to try and model it with a 21.5" diameter tire. I'm not sure how accurate this model is, but at the different voltage vs output my model is within 5% of the output power when modeling different loads at 47-48V based on that chart so I'm guessing it should be pretty close. I'm setting the amp rate for the controller at 200A so I can find the BEMF point.

These are loaded speeds with the aerodynamics of a mountain bike with full weight bike + rider at a total of 270lbs
21.5" diameter tire
50V I get 27mph @ 23A
75V I get 40mph @ 40A
100V I get 53mph @ 61A
125V I get 64mph @ 86A

Those numbers seem pretty reasonable to me, but I won't find out until I get it installed this week and try it myself. I was told this motor is good for 24 and 26" wheels so I'm hoping my amp number are on the high side, just not sure if most will have enough amps to get into the BEMF point.

26" tire diameter I'm getting these numbers from my sim
50V I get 31mph @ 33A
75V I get 46mph @ 58A
100V I get 60mph @ 91A
125V I get 72mph @ 128A

Motor looks like a hell of a climber too when I start adding grade up to 10%. Waste heat doesn't goes up, but not sky high.

Examples at 100V 10% grade for 21.5" tire and 26" tires

21.5" tire
0% grade = 53mph @ 61A, 703 watts waste heat
10% grade = 50mph @ 87A, 1206 watts waste heat

26" tire
0% grade = 60mph @ 91A, 1274 watts waste heat
10% grade = 56mph @ 119A, 2044 watts waste heat

Going to be interesting to see how close my model is.

 

[oatnet]

That sheet says they got 623 rpm from the motor at 48v, which translates to a KV of 12.98, which is where it would have to be for the Italian to have gotten 140kmh in a 26-27" wheel at 120v. However, that conflicts with Accountant's report of 9.5kv. I went from the 17" rim to the 19" rim based on 9.5kv instead of the Italian's report. If that report is for the same winding we got, and it is 13kv, you guys on the 17" moped rims are in a sweet power spot.

-JD

 

[zombiess]

That sheet says they got 623 rpm from the motor at 48v, which translates to a KV of 12.98, which is where it would have to be for the Italian to have gotten 140kmh in a 26-27" wheel at 120v. However, that conflicts with Accountant's report of 9.5kv. I went from the 17" rim to the 19" rim based on 9.5kv instead of the Italian's report. If that report is for the same motor, and it is 13kv, you guys on the 17" moped rims are in a sweet power spot.

-JD

I got the same thing just shy of 13kv, but I don't know how they arrived at 9.5kv that I used in my sim, but my sim above used 9.5k matches up rpm wise, amp wise with load. I really hope to get my motor on my bike this week and post more info.

Either way my 21.5" tire is always in the sweet spot :-D

 

[markobetti]

yes .its true WHAT OATNET IS SAYING . The factory gave me wrong kv and i only wrote it....i didnt second check it ... , we also meassured this kv..before....and Hal confirmed this on a coffie talk few days ago
Accountant , Hal and myself and few guys from Croatia have 6 more projects that we are working on together to get them moving... some are interesting as this motor ..so ones again i am sorry that stated specs are
9..5 AND THE ORIGINAL KV IS BIGGER....
So its not accountant , its me who made a mistake...

 

[gensem]

So the real number is 9.5kv, right?

 

[markobetti]

no its 13 kv... Gensem check if you want.... put it in no load speed and check

 

[gensem]

Ok, the other post was not clear on that.

Thanks

no its 13 kv... Gensem check if you want.... put it in no load speed and check

 

[andreym]

A normal 9C's distance measured from the top of the tooth to the steel hub they are pressed upon is 17.25mm.

Looks the same for CroMotor

A normal 9C's slot depth from top of the tooth(edge above the slot) to bottom of the slot is 15.1mm.

again the same here

A normal 9C's slot width is ~5.2mm (hard to measure well on my wound motor example I'm looking at).

minimum i could measure was 6mm width(tried several tooths)

The OD of the enameled wire on a normal 9C is 0.56-0.58mm (the varnish thickness varies slightly), the copper is 0.51mm 24awg.

Looks the same as well.
I measured 0.58-0.59 with the insulation

 

[oatnet]

so ones again i am sorry that stated specs are 9..5 AND THE ORIGINAL KV IS BIGGER....

Ok, the other post was not clear on that. Thanks

no its 13 kv... Gensem check if you want.... put it in no load speed and check

That is a pretty important detail to be 'confused' about, as were the 10mm flats reported as 12mm. It makes me sad that you guys reported specs that were off by 37%, because based on that information, the small fortune I just spent getting this wheelset laced into Moto rims won't yield the performance I was trying to get. Worse, I had originally sized the wheel correctly based on my projection of a 13kv-14k motor, but when Accountant posted a 9.5kv, I had to yank JRH around at the last minute to change to the bigger rims and re-order stuff.

-JD

 

[markobetti]

i understand and i am sorry ...you are right
its not accountant fault but mine.. i posted kv before checking with accountant and Hal

 

[zombiess]

So the official is now 13KV, looks like I'll be needing to swap out lower voltage higher amp controllers, but makes me glad I'm sticking with my 21.5" diameter tires.

These guys are running these same motors in their Greyborg's with 24" wheels and they seem to be doing fine based off what's been said so far. As soon as I get mine I'll start posting up as much data as possible, but 13kv puts it almost in between a Crystalite 5303 and 5302, but with much more torque and efficiency. I'm guesstimating a .08 ohm winding resistance for my simulations so it looks like if you want to run 24S you need a controller than can do 100V@100A.

With this new data and a quick remodel I'm getting 65mph @ 100V with a 94.6A current draw in a 21.5" diameter tire (Pirelli ML75s). Up a 10% grade speed drops to 59.2 mph and current draw goes to 124A, Guess someone just needs to get it on an running to get some real numbers. If the inductance is high then the amps should come down and be much easier on a controller.

I thought I saw Markobetti say he ran one on a 100V100A FET controller and got some crazy speed out of it as well. Do you mind providing us any details on what you saw current draw wise and what wheel size you ran?

 

[fractal]

So the official is now 13KV, looks like I'll be needing to swap out lower voltage higher amp controllers, but makes me glad I'm sticking with my 21.5" diameter tires.

These guys are running these same motors in their Greyborg's with 24" wheels and they seem to be doing fine based off what's been said so far. As soon as I get mine I'll start posting up as much data as possible, but 13kv puts it almost in between a Crystalite 5303 and 5302, but with much more torque and efficiency. I'm guesstimating a .08 ohm winding resistance for my simulations so it looks like if you want to run 24S you need a controller than can do 100V@100A.

With this new data and a quick remodel I'm getting 65mph @ 100V with a 94.6A current draw in a 21.5" diameter tire (Pirelli ML75s). Up a 10% grade speed drops to 59.2 mph and current draw goes to 124A, Guess someone just needs to get it on an running to get some real numbers. If the inductance is high then the amps should come down and be much easier on a controller.

I thought I saw Markobetti say he ran one on a 100V100A FET controller and got some crazy speed out of it as well. Do you mind providing us any details on what you saw current draw wise and what wheel size you ran?

I'll be running mine with the Lyen 24 FET 4115 MOSFET controller with 17 inch moped wheels and Michelin Gazelle tires (total diameter of about 23 inches). What do you think of this combo? Is it safe for the controller? Lyen says this controller is rated for 7000 watts. Thanks for any opinions.