MAC-BMC and Transmagnetics motor efficiency testing

[mrbill]

After checking the calibration on my Cycle Analyst I have remeasured the "300-watt" and "600-watt" MAC-BMC motors at 24, 36, and 48 volts. I've tested one instance of the 300-watt motor and two instances of the 600-watt motor. The 300-watt and one of the 600-watt motors don't test as being as efficient as the first 600-watt motor I modified, which I now use as my default motor on one of my bikes and the one I analyzed to generate the efficiency curves.

http://bit.ly/cVNana -- MAC-BMC 300-watt motor
http://bit.ly/cZExT4 -- MAC-BMC 600-watt motor

What strikes me is that the 600-watt motor has a remarkably flat efficiency curve over a wide range of input power (RPM), usable from about 200 watts input up to about 800 watts (at 24 volts) and doesn't really exhibit the typical gradual but pronounced drop in efficiency as the power peak is approached as can be seen in with most motors. With the 300-watt motor and with the 600-watt motor at 24 volts and at half-throttle at all voltages my controller (current limited to 50A continuous) was able to find the stall point, which occurred suddenly as the load was gradually increased past the right-most data point on the charts, efficiency going from 70%+ to zero with a small additional load. Perhaps this is a characteristic of the 18-tooth/16-pole design of these motors. It is not surprising that these motors found their way into Currie/US-ProDrive/Synergy single-speed systems.

I have a substantial investment in 24-volt batteries that I can alternately wire in series to get 48 volts for speed and power or in parallel to get twice the amp-hours for long range. If I were starting from scratch with this motor I'd probably set my system up for 36 volts as this seems to be its ideal system voltage. But, efficiency is still quite good at 24 or 48 volts. The problem with running at 48 volts is that the RPMs are quite high, requiring more gear-down to get usable power to the wheel. Also, everything gets hotter at 48 volts, putting more stress on the motor and controller. At 24 volts I can connect the motor output shaft directly to my mid-drive and avoid the losses of running power through the planetary gearbox (which I did not use for any of my tests), and everything stays cool to slightly warm unless I'm trying to push a continuous 40-50 Amps, which I don't do very often.

I've also got one of the new (ca. 2008) 4" Transmagnetics motors (TM48) tested at 24, 36, and 48 volts. Unlike the older, ca. 2000-2004 version (TM24) this newer motor is designed to run at 48 volts, but I found efficiency to be slightly better at 36 volts for moderate power levels, though considerably worse at 24 volts. Kv is around 80 RPM/Volt, while most of my other motors are about 125 RPM/volt. Also, the power phases have about 230 mOhms DC resistance, while the other motors vary from 30 to 70 mOhms, which may explain why the efficiency at lower voltages is reduced. The older TM24 is still the efficiency champ for systems where low power levels (between 100 and 400 watts input) are sufficient, especially when it is used with Transmagnetics' own controller that was designed for this motor.

http://bit.ly/aEgfzd --TM48
http://bit.ly/9VyE6b --TM24

All of these tests were conducted through the bicycle drivetrain as that is the only way that I can make these tests with the equipment I have, so if you are interested in raw motor/controller efficiency curves you'll have back out the losses due to a two-stage clean and well-aligned chain and sprocket drivetrain. Efficiency of a two-stage chain and sprocket drivetrain is between 93% and 95% depending somewhat on load, being slightly greater for higher loads and larger sprockets and slightly less for lighter loads and smaller sprockets. The charts for the Transmagnetics motors include some manufacturer's efficiency data at the bottom.

http://bit.ly/atrI3n -- Main page for hybrid bike projects

 

[sackspeed]

That´s an very interresting test. No motor reach the promises of the manufacturers.
The motors have max. 78 % which is around 85% max on the motor.
If the motor warms up it should be perhaps 80%.

 

[boostjuice]

Mr Bill, Your motor testing photographing and documentation is excellent! I commend you highly for your efforts! Thankyou for hosting your results for public viewing.

One question. How did you manage to purchase singular quantities of Transmagnetics motors? Their website suggests they only cater for large quantity orders for industrial applications. Id like to order one of their 5" motors if possible.

http://www.transmag.com/5-in-brushless-motor.htm

 

[Herrsprocket]

Hi Bill,

You said, "and avoid the losses of running power through the planetary gearbox (which I did not use for any of my tests),.

So, do you have gear boxes for these motors? Just curious what you may have found to use with them.

Tom

 

[mrbill]

That´s an very interresting test. No motor reach the promises of the manufacturers.
The motors have max. 78 % which is around 85% max on the motor.
If the motor warms up it should be perhaps 80%.

I don't have a thermometer, so a subjective description will have to do. I paused my tests when the motor faceplate near the faceplate bearing (the hottest part of the motor exposed to the outside) was hot enough that I could hold my fingers on it for a second or two, but too hot to touch indefinitely.

Over most the test duration, especially at high power, the motor was hotter than at any time I have felt it while powering my bike, especially the tests at 48 volts. I recently tested the 600-watt motor climbing a hill (1720 feet, 6.7% grade), hauling all 280 lbs of me and bike without my pedaling at a speed of roughly 10mph, consuming on average 580 watts (at 25 volts), and the motor was merely warm at the faceplate bearing.

 

[mrbill]

Mr Bill, Your motor testing photographing and documentation is excellent! I commend you highly for your efforts! Thankyou for hosting your results for public viewing.

One question. How did you manage to purchase singular quantities of Transmagnetics motors? Their website suggests they only cater for large quantity orders for industrial applications. Id like to order one of their 5" motors if possible.

http://www.transmag.com/5-in-brushless-motor.htm

Thanks. I hope readers find the information useful.

Re: Transmagnetics motors

The 5" model is probably more appropriate for a scooter or other pedal-less vehicle. If you put too much power on the bike, pedaling becomes a tiny part of the power contributed to propulsion. With the MAC-BMC 600w at 48v (or the Cyclone at 48v for that matter), pedaling becomes almost irrelevant.

I saw one of these motors used on a scooter built by ThunderstruckEV, who have or had a close relationship with one of the engineers at Transmagnetics and would get some of their overstock. That is apparently how I got my first 24-volt 4" motor. (I got one more 24v/4" TM motor as third-hand "new old stock" from someone who bought a batch of them at an estate sale and didn't need all of them.) The last motor (the 48v/4") was made available to me after my first 24v/4" motor failed when I first spun it up after it had been repaired by Transmagnetics. The 24v motors were no longer available, but the newer 48v motor was, but it wouldn't be a free replacement. It took almost 2 years for me to get it as I needed to have its shaft ground down to 8mm at the end (from 17mm) so that I could use my 8mm bore sprockets. After I received it I was told that the motor was delivered "as is" and that I would receive no further support or future "deals". I get the strong impression that they're not interested in selling to garage tinkerers. Your best bet is to contact Brian Hall at ThunderstruckEV to see if he has any stock or can get what you want.

 

[mrbill]

Hi Bill,

You said, "and avoid the losses of running power through the planetary gearbox (which I did not use for any of my tests),.

So, do you have gear boxes for these motors? Just curious what you may have found to use with them.

Tom

Hi Tom,

All of the MAC-BMC motors I bought were non-working motor units with built-in controllers. In all of the units I have worked on, it was the controllers that had gone bad; the motors themselves were functioning, so I scraped out the potting and non-working controller circuitry (where it was in the way) and dressed new cabling and installed new Halls so I could use these motors as stand-alone, externally-controlled motors.

I have part of one gearbox assembly. I have the planet carrier and the planetary gears, but I need the mounting hardware to attach it to the motor, the bolts that affix the planetary gears into the carrier, the output shaft and sprocket, and any other ancillary hardware that I may need (e.g. seals, O-rings, washers, etc.). I'm trying to scrounge around for these parts so that I can test the gearbox to see what its losses are. It's not a high priority right now as I can run these motors geared down using chain & sprocket that is less lossy than planetary gears. But, it would be nice to measure the efficiency in case it is greater than I assume (92-94%).

I would especially like to test the Cyclone/Headline motor without its gearbox, but I have no good way to mount a sprocket on the splined end of its motor shaft.

 

[Samba]

I would especially like to test the Cyclone/Headline motor without its gearbox, but I have no good way to mount a sprocket on the splined end of its motor shaft.

So the tests on cyclone motors at the hybrid site you linked, are with their usual planetary gearbox?

I know the 350,500,650 come with the gearbox and 1500 doesn't - But I don't know about the 900.

Thanks for the info and love that flexible mid drive.

Samba

 

[mrbill]

I would especially like to test the Cyclone/Headline motor without its gearbox, but I have no good way to mount a sprocket on the splined end of its motor shaft.

So the tests on cyclone motors at the hybrid site you linked, are with their usual planetary gearbox?

I know the 350,500,650 come with the gearbox and 1500 doesn't - But I don't know about the 900.

Thanks for the info and love that flexible mid drive.

Samba

Yes. All of my tests on the Cyclone/Headline motors are with the 9.33:1 gearbox. I don't have the "1500 watt" motor. The "900 watt" motor is the same motor and controller as the "650 watt" and "1200 watt" motors. Only the voltage at which the controller is driven is different. "650 watt" motor is driven at 24 volts nominal, "900 watt" motor is driven at 36 volts nominal, and "1200 watt" motor is driven at 48 volts nominal.

 

[Herrsprocket]

Hey Bill,

Thanks for the FYI's ! Is that gearbox for the Mac's a standard box but you have to find parts for, or is it something you are cobbling together from scratch?

Tom

 

[mrbill]

Hey Bill,

Thanks for the FYI's ! Is that gearbox for the Mac's a standard box but you have to find parts for, or is it something you are cobbling together from scratch?

Tom

Tom, the parts I have are for the standard gearbox. I just need to find the additional parts to make it usable.

 

[sackspeed]

mrbill wrote:
Over most the test duration, especially at high power, the motor was hotter than at any time I have felt it while powering my bike, especially the tests at 48 volts. I recently tested the 600-watt motor climbing a hill (1720 feet, 6.7% grade), hauling all 280 lbs of me and bike without my pedaling at a speed of roughly 10mph, consuming on average 580 watts (at 25 volts), and the motor was merely warm at the faceplate bearin

This ist the right use for this motors. In Germany this motors are sell mostly for velomobile and recumbents (500W,24V/36V) and work fine. But 900W or more is to much.

 

[Herrsprocket]

Tom, the parts I have are for the standard gearbox. I just need to find the additional parts to make it usable.

Wait a second, wait a second ! What ?! This is a possible game changer here. Ok, let me catch my breath. So this is a standard production gearbox for the BMC type motor, just bolts right up,, meshes perfectly with the output shaft and all that good stuff? If that is the case, wow, where have I been and where does one find it?

See, my surprise is that I was looking for the BMC motors with a gearbox some time ago (looking at them for several years now), and the last time I asked Chandu at BMC about them, he said they were not in production yet ( I asked about a year and a half ago). I saw on their website the picture of one of their motors with a gearbox attached and that was when I asked Chandu about it. Nope he says, not ready, still working on it. That was when I made my decision to go after the Cyclone products, a ready to go motor with gearbox. I have since then not been aware that a BMC gearbox has come out. On the other hand, is this gearbox made for the Mac motors, and not really a BMC product? Is that it, is that it?

I think most of us would agree that the BMC products are of very good quality, and even though the Mac motors are from the same lineage, I am not sure if they are up to the same standards, but I suspect they are quite close if not the same. And we all have some mixed feelings about the Cyclone products, they can be just fine for some, and for others, eh, maybe not so great, but they work.

So William, is this a BMC gearbox or a Mac gearbox? And where did you find it?

Wringing hands together,,,,,,

 

[mrbill]

Tom, the parts I have are for the standard gearbox. I just need to find the additional parts to make it usable.

Wait a second, wait a second ! What ?! This is a possible game changer here. Ok, let me catch my breath. So this is a standard production gearbox for the BMC type motor, just bolts right up,, meshes perfectly with the output shaft and all that good stuff? If that is the case, wow, where have I been and where does one find it?

See, my surprise is that I was looking for the BMC motors with a gearbox some time ago (looking at them for several years now), and the last time I asked Chandu at BMC about them, he said they were not in production yet ( I asked about a year and a half ago). I saw on their website the picture of one of their motors with a gearbox attached and that was when I asked Chandu about it. Nope he says, not ready, still working on it. That was when I made my decision to go after the Cyclone products, a ready to go motor with gearbox. I have since then not been aware that a BMC gearbox has come out. On the other hand, is this gearbox made for the Mac motors, and not really a BMC product? Is that it, is that it?

I think most of us would agree that the BMC products are of very good quality, and even though the Mac motors are from the same lineage, I am not sure if they are up to the same standards, but I suspect they are quite close if not the same. And we all have some mixed feelings about the Cyclone products, they can be just fine for some, and for others, eh, maybe not so great, but they work.

So William, is this a BMC gearbox or a Mac gearbox? And where did you find it?

Wringing hands together,,,,,,

Tom:

The nice thing about the BMC motor is that its output shaft has a tip that has a reduced diameter of 8mm (from 10 or 12mm) and a convenient flat that allows one to affix a #25 sprocket with 8mm bore with as few as 9 teeth. In combination with a sufficiently large corresponding sprocket and for operation at 24 volts nominal, one can get away without using the gearbox and enjoy the improved efficiency. If you're running at 36 volts or higher, then you probably will need the gearbox to get motor speed down low enough to be usable, even for a mid-drive. My interest in the gearbox presently is to test its efficiency and see just how much power is lost through it under various conditions.

I've been told this planetary gearbox is made by a third party and sold under various brand names. It's not a BMC product. You can find it at electricscooterparts.com for $179 brand new (sold as Lashout gearbox on the sprockets page), or you can find it in parts from other various sources. All Electronics has the planetary gear assembly (w/o housing) for less than $10. I got my "non-working" motors and the gearbox housing from Pacific Avenue Cycles in Santa Cruz, CA. They are the repair shop for and neighbors of an electric bike rental and sales outfit adjacent to the Beach and Boardwalk, so they get a steady stream of broken, not-so-broken, and other odd and sundry parts for these motors, some of which they make available on Ebay from time to time. I've also seen this gearbox on Ecospeed's motors.

No. Teeth:
Sun gear: 20
Planet gear: 28
Ring or Annulus gear: 76

Gear ratio when input is at the Sun gear:
1/ (1 + (Ring gear) / (Sun gear)) = 1/(1 + 3.8) = 1/4.8 = 0.2083333...

Here's a photo of what I have.

 

[Ariane]

Hi Guys,

Just like to resume the information I have found here a single Cyclone 650-1200 Watts motor can output 1200 Watts at 48 Volt.

The gear box on this motor is not really good and did last long, but the motor seem ok the rest of the Cyclone kit is crap and their controller has seriously tendency to blow out when you use them at low RPM.

Did I miss something? Good day!
Black Arrow

 

[Rayy]

I got my planetary gearbox from Scott at evdeals.com. This one has a bearing support for the sun gear and a larger dia sprague clutch. I can't tell if the one at electricscooterparts.com has the same features but it looks like it only has a bronze bushing support.

If I remember correctly, when I check the power consumption spinning a Kollmorgen motor at full speed no load, with and without the planetary gearbox, the power difference was only 2-3 watts. I think is was around 41-42 watts without and 43-44 with the gearbox. I did clean out the thick heavy grease that came with it and used a lighter synthetic grease for this test. I don't know what the % power difference would be under load.

This gearbox fit the Kollmorgen and MAC600 perfectly, but the MAC300 motor shaft was a bit longer and I had to use washers to space it out so it wouldn't bind. I never did manage to get ahold of a Transmagnetics motor, but according to the drawings, the bolt mounting diameter was larger so this planetary would not fit. Mrbill, can you clarify this and how did you mount this?

 

[Miles]

I've been told this planetary gearbox is made by a third party and sold under various brand names.

AFAIK, it's a Matex unit: http://www.matexgears.com/index.html

 

[mrbill]

I got my planetary gearbox from Scott at evdeals.com. This one has a bearing support for the sun gear and a larger dia sprague clutch. I can't tell if the one at electricscooterparts.com has the same features but it looks like it only has a bronze bushing support.

If I remember correctly, when I check the power consumption spinning a Kollmorgen motor at full speed no load, with and without the planetary gearbox, the power difference was only 2-3 watts. I think is was around 41-42 watts without and 43-44 with the gearbox. I did clean out the thick heavy grease that came with it and used a lighter synthetic grease for this test. I don't know what the % power difference would be under load.

This gearbox fit the Kollmorgen and MAC600 perfectly, but the MAC300 motor shaft was a bit longer and I had to use washers to space it out so it wouldn't bind. I never did manage to get ahold of a Transmagnetics motor, but according to the drawings, the bolt mounting diameter was larger so this planetary would not fit. Mrbill, can you clarify this and how did you mount this?

I haven't tried mounting it yet. Still waiting to acquire all of the parts. I'm only planning to try it on the BMC motor(s), not on the TM motors.

Power lost under load is what is interesting.

 

[mrbill]

I've been told this planetary gearbox is made by a third party and sold under various brand names.

AFAIK, it's a Matex unit: http://www.matexgears.com/index.html

Thanks for the link.

Matex claim 98% efficiency for a single stage of reduction. We'll see.

 

[mrbill]

Hi Guys,

Just like to resume the information I have found here a single Cyclone 650-1200 Watts motor can output 1200 Watts at 48 Volt.

The gear box on this motor is not really good and did last long, but the motor seem ok the rest of the Cyclone kit is crap and their controller has seriously tendency to blow out when you use them at low RPM.

Did I miss something? Good day!
Black Arrow

If you're running for a long time under load at 48 volts try adding cooling fins or remember to occasionally drip water on the outside of the case. Also, the planetary gearbox runs quieter and cooler (but slightly less efficiently) if you pack it with more grease. I use red high-temp grease with a teaspoon of 30wt motor oil. Better is to run it at 24 volts (nominal) as I have been doing for several years and never broken anything significant. The only other part of the Cyclone kit I've used is the motor mounting bracket "L", and have not broken one of these yet in spite of the high torque that they have to endure.

I don't think these motors were designed to run higher than 30 volts (24 volts nominal). I have run them at 48 volts both on the road and on the bench, and they run very hotly at 48 volts, even under moderate load. At 48 volts the controller gets hot when used at partial throttle, something you'll be doing more of if you intend to pedal while motoring. They will put out the power until they overheat and shut down (or worse).

The best feature of the Cyclone/Headline motor is that in a compact package you get a reasonably efficient and not too expensive "300 RPM/ 1HP" motor that gives the user more mounting options than one gets with a larger motor such as the BMC. If you use it within its design limits you'll get a long life out of it.

 

[Ariane]

Hi Mrbill,

THX for the information, if I need 1200 watts under load is better to use (2) motor at 650 Watts at 24 Volt (30 volt nominal). I like to build something like the Conway ebike but I didn't have any experiences with the Cyclone motor.

My ides is to use a 3 speed nexus hub for top speed of around 60-70 Km/h do you think that I can do that with theses 2 motors at 30 Volt nominal because I want a reliable set up and something that can last for years.

Thank you, good day!
Black Arrow

 

[boostjuice]

Hi Mrbill,

THX for the information, if I need 1200 watts under load is better to use (2) motor at 650 Watts at 24 Volt (30 volt nominal). I like to build something like the Conway ebike but I didn't have any experiences with the Cyclone motor.

My ides is to use a 3 speed nexus hub for top speed of around 60-70 Km/h do you think that I can do that with theses 2 motors at 30 Volt nominal because I want a reliable set up and something that can last for years.

Thank you, good day!
Black Arrow

Yes, 2 x "650W" (external controller) Planetary geared motors @ 8S lipo (29.6V) = 60~70kph Planet gears would last quite a long time as well :wink:

 

[Ariane]

Yes, 2 x "650W" (external controller) Planetary geared motors @ 8S lipo (29.6V) = 60~70kph Gears would last quite a long time as well :wink:

Cool but I never said that i wil be using the planetary gear box that came with the motors, in fact I don't need them :wink:

Good day!
Black Arrow

 

[boostjuice]

Thats fine, but in any case i had to differentiate between that type of Cyclone/Headline motor (with attached planetary gearbox) from the larger version (no planetary gearbox) :wink:

 

[Ariane]

Thats fine, but in any case i had to differentiate between that type of Cyclone/Headline motor (with attached planetary gearbox) from the larger one (no planetary gearbox) :wink:

Boostjuice a (2) stage reduction drive is the key to use those (2) motors without their planetary gear box in mind, please tell me if i'm wrong. This way both motor are shorter in lenght and can easily fit between crank, and with both motor i can output more power than i single 1500 Watts (larger one) motor is able to do right ?

Good day!
Black Arrow