8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

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zappy   100 W

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8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by zappy » Nov 16 2013 7:53am

This is a quick comparison of version 1 and version 2 and 3. There have been a few iterations of the cro motors over time, some minor tweaks to the axels, spoke holes, hub off sets etc, and then the later version 2 and 3 which looks quite similar on the outside but has totally different innards. My preference is for off road riding on downhill style bikes, and with over 8 inches of rear travel unsprung weight is VERY noticeable. Brian, Pickle and I pulled apart several version 1 and version 2,3 motors to compare. The 1st thing you notice is the weight!
Version 1 cro motor 10.6KG, lamination thickness 0.5mm, copper wind 18 strands 4 turn, stator width 50.3mm
PA270055.JPG
Version 1 Cromotor 10.6KG
PA270055.JPG (60.01 KiB) Viewed 8595 times
PA270075.JPG
0.5mm lamination thickness
PA270075.JPG (68.08 KiB) Viewed 8595 times
PA270066.JPG
version 1 stator width 50.3mm
PA270066.JPG (57.31 KiB) Viewed 8595 times
PA270080.JPG
version 1 18 strands of copper 4 turn
PA270080.JPG (99.63 KiB) Viewed 8595 times
Version 2,3 cro motor 12.2KG! Lamination thickness 0.35mm!, copper wind 18 strands 4 turn, stator width 48.3mm
PA270062.JPG
version 2 Cromotor 12.2kg
PA270062.JPG (63.84 KiB) Viewed 8595 times
PA270071.JPG
0.35mm Laminations
PA270071.JPG (73.63 KiB) Viewed 8595 times
PA270064.JPG
Version 2 stator width 48.3mm
PA270064.JPG (57.06 KiB) Viewed 8595 times
PA270079.JPG
version 2 18 strands of copper 4 turn
PA270079.JPG (80.42 KiB) Viewed 8595 times
The newer versions had much finer laminations and a LOT smaller stator inside diameter (this is where most of the (unnecessary?) pork is). The stator teeth are also about 2mm longer, but it still has the same copper fill/wind and the obvious beefy alloy hub. This would be a much superior heat sink.
Brian and I put the flux rings up in the old lathe and machined off most of the original spoke flanges and turned the rest of the flux ring down to only 3.1mm thick (this is a lot of steel removed). We then redrilled some new spoke holes in the new minimalist spoke flange. There was no noticeable flux leakage after this only when I assembled the flux ring back onto the stator you can feel a slight amount. Weight loss is just under 2KG! I also had a 500w golden motors freewheel side, side plate laying around which is thinner and without the Cro motors big steel freewheel adaptor hub (only the bearing diameter needs machining to suit, and the bolt holes drilled larger for the Cro motors larger bolts)that saves another 250g. Some cooling holes were also drilled. The KV has not changed; it is still 9.3KV, this gets the early version down to 8.4KG! And the later model down to approximately 10.2KG. Don’t get me wrong this is still a big lump for jumping etc, but I think anyone could feel the difference on or off road and it has to be kinder for rear wheel pinch flats and rim damage etc.
PA270086.JPG
machining down Brian's version 3 flux ring (a lot!)
PA270086.JPG (61.07 KiB) Viewed 8595 times
PA270087.JPG
You can see the much smaller and thinner spoke flanges.
PA270087.JPG (46.63 KiB) Viewed 8595 times
Checking the difference in no load losses: Brian and I connected the different versions up to a little 18fet controller and 24s of A123, and measured the no load losses of a bare hub no tyres, rim, or spokes, using a Cycle Analyst and 80 volts.
Version 1: 200Watts
Version 2,3: 131Watts!
A very knobby tyre, rim and spokes adds around 50watts depending on diameter and tread etc.
The version 1 does have 4% more stator width.
If maximum efficiency is when copper losses = no load loss, does this mean the point of maximum efficiency of the version 1 cro motor is overall obviously lower, but happens at a overall higher output? If you use high voltages the difference is going to be a LOT bigger. My wife’s bamboo bike was using around 700w at 120V or 145km/hr free rpm with a V1.
Off road with average speeds of only around 25km/hr in the bush the difference in losses would be slight, and it might be lighter to just carry more battery and use the old version. Commuting at high speed, using high volts, or small wheels the opposite may be true.
Which version would people choose? Whats your priority?
Zappy

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by zappy » Nov 16 2013 8:10am

Here is a finished wheel. 20" double wall BMX rim (thanks Brian!) and 16" motocross tyre. I could make a drawing up if people are interested for the exact sizes we machined the flux rings.
Zappy
Attachments
PB020002.jpg
PB020002.jpg (86.55 KiB) Viewed 8587 times
PB020003.jpg
PB020003.jpg (84.02 KiB) Viewed 8587 times
PB020005.jpg
Notice the spokes are very very close to the new flux ring outer diameter.
PB020005.jpg (72.17 KiB) Viewed 8587 times

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by Teh Stork » Nov 16 2013 8:21am

If maximum efficiency is when copper losses = no load loss, does this mean the point of maximum efficiency of the version 1 cro motor is overall obviously lower, but happens at a overall higher output?
As you do not have copper-resistivity data, copper losses cannot be calculated. If the mean load during use is 2000W, with 200W of it being parasitic losses and 400W being copper losses - decreasing copper losses should take priority. When comparing cost, decreasing hysteresis losses (better grade of electrical iron) and copper losses (more copper) are normally more expencive than decreasing eddy current losses (thinner laminations).
2013 VW E-UP!
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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by zappy » Nov 16 2013 8:50am

84.5 milliohm

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by liveforphysics » Nov 16 2013 3:07pm

That's fantastic. :-)

Awesome how low the no-load is on the newer gen as well. Anyone have good data on one filled with a bit of ATF?
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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by neptronix » Nov 16 2013 3:47pm

Excellent science as usual, thanks zappy
Efficiency is everything :bolt:

My first major build: 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w on a Turner O2 full suspension.
The monster scooter: ? on a Cannondale Semi Recumbent.

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by zombiess » Nov 17 2013 2:11am

You machined only the steel, correct?
Thanks for posting up your test results.

BTW, if anyone is interested in the inductance differences,
V0/V1 is ~120uH
V2/V3 is ~145uH

I measured the phase to phase resistance at ~75mOhm using a 30A CC source.

Since I have my V2 running in a 19" MC wheel 25.3" tire, I haven't managed to get the covers warm yet, but I'm only running 7.5kW peak with a top speed of 43mph on 74.x volt fresh charge.
My V0 in a 20" BMX with moped tire (20.5" diameter) would get pretty warm after beating on it at 125V@>150A peaks. I have a V2 in a 16" moped rim with the same tire, just haven't played with it. I have a temp probe installed though for whenever I do get around to playing with it.

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by madin88 » Nov 17 2013 4:03pm

i would take the newer version. low no load losses and thin laminations are always good.
Does v2/v3 not also have better iron material? Can anyone confirm?

Are there any infos about Cromotor V4 / Vortex or Cromotor Mammoth (they should come out next year)?
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by moonshine » Nov 19 2013 5:40pm

just got my cromo v3 laced into a 19" prowheel by jrh. My cromoV1 is in a 26" large marge and gets peaks of 10kw when getting up to 50mph and after a few stop and gos like that in DC, it gets pretty hot.

Does anyone know if the cromo v3 comes with a temp probe installed? phases, 2 sets of halls, and a temp probe?
Current Build: Vector, MXUS 4T in 19" moto, Max-E, 20s8p Samsung 25R http://endless-sphere.com/forums/viewto ... =6&t=67752

Torque Raptor, Cromo V3 in 19" prowheel, Kelly KBL96251, 24s4p (SOLD) http://endless-sphere.com/forums/viewto ... =9&t=56342
Giant DH Comp, X5404/Cromo V2 in 26" rim, Kelly KBL96251/Lyen 18fet, 24s4p (SOLD) http://endless-sphere.com/forums/viewto ... =6&t=40031

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by madin88 » Nov 20 2013 4:37am

moonshine wrote:just got my cromo v3 laced into a 19" prowheel by jrh. My cromoV1 is in a 26" large marge and gets peaks of 10kw when getting up to 50mph and after a few stop and gos like that in DC, it gets pretty hot.

Does anyone know if the cromo v3 comes with a temp probe installed? phases, 2 sets of halls, and a temp probe?
i think the v1 is less efficient due to the thicker laminations..

Yes, v3 comes with all you asked. Dropout wide is different as far as i know..
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
- KTM Hardtail Pedelec / eZee V2 6T / 27,5" / Kelly KBSX @ 1,5kW / Torque PAS / CA-V3 / 13s4p Sanyo GA in Shark case

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8.4KG CROMOTOR & COMPARISON OF V1,V2,V3(with drawing)

Post by zappy » Mar 10 2014 5:30pm

Drawing of modified Cro motor flux stator ring. I have made 3 similar to this. Machining off the original spoke flanges and re drilling spoke holes seems like a bit of a hassle but this saves around 350grams and it doesn't really take very long. You also have the option for different spoke counts and spoke hole diameters etc. You can mark out the new spoke holes using the original holes still just show after machining the flange off to this diameter, and then just centre punch carefully by hand and redrill by hand and chamfer. The crystalyte motors and 9C clones would have very similar dimensions only narrower. Using slightly modified 9C side plates with the associated smaller bike size bearings and modifying the inner axel as it has a fair bit of pork (electric scooter architecture) could save a little more.

Zappy
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DSCF6223.jpg
DSCF6223.jpg (47.59 KiB) Viewed 7816 times

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by spinningmagnets » Mar 10 2014 5:50pm

Ventilating a hub motor continues to gain favor with performance builders, and for that modification I would recommend spraying the interior with the anti-corrosion coating. The performance example is an automobile alternator, which has a skeletonized frame and exposed windings to let heat out, so the principle is well-proven to work.

As Luke mentioned, there is also liquid-cooling with ATF. There is some debate about a geared hub because of the drag from a 5X speed rotor, but if you don't mind an occasional leak, the ATF cooling is reported to work quite well, with the added benefit that it does not allow outside dust and debris inside the hub (a concern expressed by some about air-cooling).

Shameless plug for my article on the Cro: http://www.electricbike.com/cromotor-mo ... ric-bikes/

WHEEL and TIRE selection
The Cro is the most popular hub for the Raptor, here are some recommendations for the Cromotor, the following quotes from ES members “Rix”, “snellemin”, and “offroader”:

“…I have now tested 16 different tires. I keep going back to the Shinko SR 241 because they are the best on both the road and dirt. A knobbie works better on the dirt, and the M62 Michelin works better on pavement. But no tire works better than the SR241 on all types of terrain….That is the best tire I have tested to date in sizes 2.75 X 19, 3.00 X 17, and 2.75 X 17…”

“…I went with the Prowheel rim and Shinko 241 tires...a 10.5 shock and 19″ Prowheel is perfect setup..."

“…There is also no reason to use a heavy dirtbike tire and wheel on the front, when a bicycle tires will give you far better selection, and weigh much less. Bicycle tires I find work well on the front, and never pinch flat and also wear very slowly....This is only for front tires, for the rear…a dirt-bike tire is a must! You should really only use a 19″ prowheel rim in the rear…”

“…After the big problems with bicycle rear tires pinch-flatting all the time and wearing away too quickly, the Shinko 241 is a dream tire. Both the 241 Shinko 19 X 2.75...have held up really well to constant abuse. I am talking about hitting curbs and steps at high speeds..."

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by Dark Knight » May 22 2014 7:56am

A wealth of good info here - subscribed for future reference.
Will be looking at possibly taking some pork off the Cro when she arrives...

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by John Bozi » May 23 2014 12:27am

zappy wrote:Here is a finished wheel. 20" double wall BMX rim (thanks Brian!) and 16" motocross tyre. I could make a drawing up if people are interested for the exact sizes we machined the flux rings.
Zappy
Subscribed.

Zappy I am radially lacing my crystalyte 4065 in a 19" bicycle trials rim, so I am very interested how your spokes and rim are holding up, please let us know if you have any spoke or rim problems...

thats a monster looking motor man.

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by ecruz » May 28 2014 11:36pm

Interesting thread so what was the end result? What difference did you end up with?

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by macribs » Aug 02 2014 4:38pm

Did you do any tests to see if the weight shavings gave any performance peak? Like faster acceleration?
What about tire wear? Any noticeable changes? What about heat build up? Less material to transfer heat to could mean higher temperatures after shavings.

So to the less measurable things. The overall feel of the bike after those shavings.
Easier handling in rugged terrain? Better downhill capabilities?

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by macribs » Aug 12 2014 5:57pm

zappy wrote:Here is a finished wheel. 20" double wall BMX rim (thanks Brian!) and 16" motocross tyre. I could make a drawing up if people are interested for the exact sizes we machined the flux rings.
Zappy

Great work shaving off the weight.
I think in another thread here on the forum I saw a guy with carbon fiber covers for the motor and the weight save was high on that as well.
Around a kilo total. Might not be ideal as for heat build up, so the thread I read he had liquid cooling of the hub motor.

Maybe there can be even more grams shaved off?

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by karelski » Aug 22 2014 8:11am

Hi Zappy, could you make some short comparision of Cromotor and Magic Pie motor? You have modified both motors, so you have some skills as usage of these motors for offroad bikes. I have Magic Pie with 72V, 15Ah battery and Kelly 72, 55A, max.135A controller on my DH bike and speculate to try Cromotor...
Is Cromotor so much more better?

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by MAGICPIE3FOCUSPOWER » Oct 27 2014 5:36am

Anyone has some pictures of the V3 motor?
Are any big differences between V2 and V3?

Thank you 8)
Nothing is perfect until I touch it...

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by madin88 » Oct 27 2014 2:48pm

MAGICPIE3FOCUSPOWER wrote:Anyone has some pictures of the V3 motor?
Are any big differences between V2 and V3?

Thank you 8)
the main difference is V3 has a thermistor installed. the stator, winding etc is all the same so same power and efficiency.
with V3 there is a normal (like V2) and one with a wider axle for wider dropouts.

Other small changes:
no holes for bicycle spokes anymore, better painting, small changes on the axle at the point where the wires are coming out (a bit less weakening of the axle there), zinc plated steel parts and screws.
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
- KTM Hardtail Pedelec / eZee V2 6T / 27,5" / Kelly KBSX @ 1,5kW / Torque PAS / CA-V3 / 13s4p Sanyo GA in Shark case

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by MAGICPIE3FOCUSPOWER » Oct 27 2014 11:48pm

Thank you 8)

This mean I can't use 13G spokes only 12G spokes usable?
I see there are two version of V3: 145mm and 155mm.

Are any differences between these two axles versions except the axle length?

Thanks!
Nothing is perfect until I touch it...

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by madin88 » Oct 28 2014 10:08am

MAGICPIE3FOCUSPOWER wrote:Thank you 8)

This mean I can't use 13G spokes only 12G spokes usable?
I see there are two version of V3: 145mm and 155mm.

Are any differences between these two axles versions except the axle length?

Thanks!
for cromotor better use moped rims and strong spokes. 11/12ga butted spokes from JRH are good.
no, from what i know only the axle length is different nothing else.
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
- KTM Hardtail Pedelec / eZee V2 6T / 27,5" / Kelly KBSX @ 1,5kW / Torque PAS / CA-V3 / 13s4p Sanyo GA in Shark case

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by MAGICPIE3FOCUSPOWER » Oct 28 2014 11:16am

Thanks mate! 8)
Nothing is perfect until I touch it...

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Re: 8.4KG CROMOTOR & COMPARISON OF V1,V2,V3

Post by crossbreak » Jan 23 2016 1:47am

Subject: Motor comparison spreadsheet
crossbreak wrote:Data for current Cromotor

Winding: 4T 30 Strands
16 pole pairs
Kv: 11.1 with trapezoid controller (x8m06c 12Fet)
0.35mm lams
233mm spoke flange BCD

No load data:
2.375 A
43.45 V
481 rpm

2.072 A
17.17 V
190.5rpm


Finally a motor with a Km of almost 20. Almost double of a MXUS3000 and Hubmonster was beaten, at least in terms of Km :shock: they managed stuff quite a lot of copper into this thing. looks very similar to the QS205 V3 if you ask me BTW

special thx to merlin who provided the motor. @merlin It would be very nice if you would upload a pic of the internals.

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