12T MAC motor and high current

mischael

100 µW
Joined
Jun 6, 2013
Messages
9
I'm new here. I'd like to add electrical assist to a velomobile. Because of legislation, I get a 25kph limit (with 500W continuous, 1000W max power), which is still nice for climbing hills and stop-and-go. I thought of getting the 12T MAC motor, because 200rpm seems to be just shy of 25kph. Would it be too much to feed it 40 Amps? I guess this would result in great torque, but would it be too much for the internal gears? Should I opt for a less powerful setup?
 
I honestly don't know the answer to your question, but I've never really heard of this sort of idea being an issue. I am no master of ebikes, and I am sure the cogs do eventually wear out. One thing is for sure, the cogs are typically run dry, adding some sort of grease or lube would probably help lots with both friction and noise. I am sure someone on this forum has some knowledge on this subject, but maybe you could e-mail the people selling the motor as well.

25kph is a ridiculously low limit. The way ebike laws are often written (most of the laws I've read at least), they say you cannot exceed whatever speed no matter what. That is to say that with an ebike motor installed, you'd no longer be allowed, with pedaling alone, to exceed a certain speed. That seems absurd as there aren't many cyclists that cannot exceed 25kph with pedaling alone. You should keep in mind, the ebike that goes 25kph with a mountain bike (this is typically the kind of information used when they try and say how fast a motor will go at whatever voltage) will go faster in a velomobile. Also, they often site the motor will go a specific speed, but (this might be obvious) a higher voltage battery pack means you go faster as well. http://ebike.ca/simulator/ This tool might help.

Personally, I think I wouldn't worry tremendously about the speed limits, especially when you have something like a velomobile. It's be very hard for anyone to tell that you had anything electrical beyond someone in the know, on top of that, anyone who sees you going particularly fast would surely guess it's because you are using a velomobile and not some insane ebike setup. This is just what I would do though, maybe in your area, they are really focused on keeping ebikes from breaking the rules or something.

What velomobile do you have? It'd be pretty cool to have a velomobile ebike, I am a little envious.
 
I'm living in Switzerland, and although the motor may only assist until 25kph, you are free to drive as fast as you want on your own. I will buy a Leiba X-Stream, which is what I think the best compromise of speed and versatility. Unfortunately, I'll have to wait for half a year until I get it (manufacturer is builing a new workshop - no new vehicles until then).

I think I will get the 40A controller and battery and just configure it for a lower current and see how it goes. Most of the time the motor will sit idle anyway when I'm driving more than 25. I thought about ignoring this speed limit, but a velomobile is far from stealthy so running into some curious cops is likely. Especially because it makes a lot of noise even without a motor.
 
If you haven't ordered the motor yet, I recommend adding the factory-installed temp probe for $15. Geared hubs have a poor heat-path for shedding to the motor shell. Since you are in a very hilly place and desire the type of performance that comes from 40A, you might research other configurations.

One idea is to add oil to roughly 1/3rd of the interior volume of the MAC, to improve the heat-path from the stator to the aluminum motor-shell.

Another great hill climber (I'm told) is the 20-inch Magic Pie with an external controller. (also definitely add a temp probe and perhaps add oil-cooling in the future if it is getting too hot under your user-profile?).

Last, consider a non-hub of some type. The stock (and affordable) GNG Gen-1 has several weaknesses, but each weakness has been addressed by ES member LightningRods, who has developed an upgrade package. The stock motor appeared to fill an unserved niche, and after a couple dozen ES members have abused it heavily, it has turned out the be a real gem when used at 48V-72V. This motor reaches saturation at just above 30A, but the ability to give the motor the use of the gears allows the rider to downshift and easily climb some surprisingly steep inclines without overheating.

I have recommended the MAC 10T at 48V to many riders with mild hills (normal/average hills), and so far the reports have all been positive. Having half their commute pass over fairly flat land allows this geared hub to cool down before the next hill. However, if your hills are steeper and longer than my hills, I fear you might be disappointed by this well-made product (even after wisely selecting the 12T), which simply doesn't have the copper mass or heat-shedding to survive long-term 40A continuous operation.

Whatever you choose, I highly recommend some type of heat probe and using a CycleAnalyst to control and adjust the amp-limits, based on a heat-setting that will roll back the max amps allowed...so your kit will survive your evaluation test-runs. Better to sell a kit that doesn't fit your life and buy something more suitable, than to throw away a fried motor/controller ($300 wasted, could have sold for $200?)
 
I haven't ordered yet but will certainly order a cycleanalyst and also the upgraded version with the temperature sensor, since cost is not that huge an issue when buying a 10k$ bike. I first wanted to take the BMC, but it is not that great for <25kph only. This way I can check how hot it will get on my local hill (10% over 1.5km). I used the ebikes.ca simulator with the BMC2_Trq motor, and according to this it does not overheat when pedaling with 200W, which is realistic for short periods. Of course, it's not the same hub, but as I gathered it should be roughly similar (I guess this BMC is 10T).

The MagicPie at 25 kph (24V) only delivers 250W, which is not much. I'd like to have as few issues as possible and the vendor of the velomobile said the cyclone would wear out the transmission pretty quickly. I guess it is similar with the GNG. The noise is another issue. A velomobile amplifies all noise quite a bit, so with a noisy motor it may get to uncomfortable levels, especially if the motor is inside the driver's cabin. I thought about the sunstar, but I'd like to have a Schlumpf bottom bracket for maximal gearing range. Since I only need assistance up to 25 kph, I do not gain much from a non-hub setup, which is otherwise very nice together with a speedhub.

Unfortunatly, I don't have a workshop so I'm not able to do any modification to the hub.
 
I don't think you'll have much problem with MAC 12T at 40amps 25km/h. Just check the temperatures for a while to make sure it's not getting too hot. My MAC 10T climbs hills really well at 40amps 52V 2080Watts.

Do you care about controller amps? 40amps at 36v is 1440W peak @ the controller. Obviously would be lower at the wheel due to inefficiencies.
 
Hi there :)
I have had a lot to do with the mac motors as they were still cheap. Anyway, a 12T mac is REALLY a torque motor. You don't have any fear to get about getting hot if you keep it under 25Km/h really nothing, even completely loaded (I used them for cargo bikes in Germany). The new gearing is also very strong.. nothing to fear again.
Now a few things I would like to point.
First, If you really want to keep it under 25km/h you will have to push all your extra weight (4,5Kg motor + 500g controller + 3-5Kg 36V10Ah battery) after this limit. Velomobile are made to ride at least 35-45km/h, this is probably your goal.
I would strongly recommend you to digg for "middle motor" or anything you could put between your legs and the last reduction. This will give you the possibility to have a drive which will run in his best efficiency all along and if you ever for some diverse reason (living in another country, riding on closed roads...etc) you can simply remove the limitation with one button or quick programming of the CA.
One last point. Such motors don't allow regeneration (regen), your Leiba with his 35Kg and you inside + the electric drive would allow you to really get some regen. I use it today on my cargo bike and I get 10-13% in town back and 5-10% on the ride... it also makes a great difference on the brakes pad life and that's really something when you are heavy loaded ;)
Was just my two cent though!
hope it helps,
Gruß,
h.
 
Personally, I'd like a mid drive a lot more. But the fact is, that I may not use it for more than 25 kph. The sunstar seems decent, but only delivers 250 Watts and is proprietary. Adding a cyclone would be possible, but I do not want to have a hornet's hive in there. I'm not sure about the modified GNG V1, but I can't make major modifications. All other mid drives are either very expensive (ecospeed) or not available for purchase in small amounts.

With the MAC I have something that is not expensive and if the 25 kph limit on trikes gets removed some day I can just exchange it with a faster version (or a crystalyte direct motor to get regen).
 
Well, maybe I'm going for the 10T motor, since I'd like to have a high speed also on the hills, and the 12T motor may there be more efficient but slower. Does anyone know whether the BMC V2 Trq is 10T or 12T?
 
mischael said:
Well, maybe I'm going for the 10T motor, since I'd like to have a high speed also on the hills, and the 12T motor may there be more efficient but slower. Does anyone know whether the BMC V2 Trq is 10T or 12T?
Is more like a 10T... i have a 12T MAC with a 40A controller and 16S lipo, it´s a beast! Not fast, but definately torquey!
 
If you have any choice of velomobiles, I would go with one with a 20" (406mm) rear wheel. You will get much greater effeciency with it for your rear hub motor. If you want quiet, a DD (direct drive) hub is much quieter and generally less costly than a geared one. Again the smaller the wheel the greater the torque and easier time the motor has at lower speeds. Most trikes and velos use a 20" rear wheel, especially for electric conversion.
otherDoc
 
I just bought the 12T from Cellman. 24 Inch wheel. 9 Fet controller that I plan to run at 60v.

I will do an unboxing and review when it gets here.

Now, time to get stupid.....my next move is to buy the Bafang750w crank drive and fit it to the same bike :D

Should be a total stealth-torque beast, 1500w on tap any given time. Perfect for London.
 
The Mighty Volt said:
I just bought the 12T from Cellman. 24 Inch wheel. 9 Fet controller that I plan to run at 60v.

I will do an unboxing and review when it gets here.

Now, time to get stupid.....my next move is to buy the Bafang750w crank drive and fit it to the same bike :D

Should be a total stealth-torque beast, 1500w on tap any given time. Perfect for London.

Are you sure the MAC freewheel cover can withstand the torque from the Bafang? I damaged mine by mashing up hills.

I'd imagine the Bafang generates far more torque than someone stamping on the pedals.
 
Joseph C. said:
The Mighty Volt said:
I just bought the 12T from Cellman. 24 Inch wheel. 9 Fet controller that I plan to run at 60v.

I will do an unboxing and review when it gets here.

Now, time to get stupid.....my next move is to buy the Bafang750w crank drive and fit it to the same bike :D

Should be a total stealth-torque beast, 1500w on tap any given time. Perfect for London.

Are you sure the MAC freewheel cover can withstand the torque from the Bafang? I damaged mine by mashing up hills.

I'd imagine the Bafang generates far more torque than someone stamping on the pedals.

I'm not sure, at all, but I guess there is one way to find out.

What's the story with this weak ass freewheel cover then...thanks!
 
The Mighty Volt said:
I'm not sure, at all, but I guess there is one way to find out.

What's the story with this weak ass freewheel cover then...thanks!

True. They're only $15 dollars for a replacement.

The aluminium is fairly thin near the screws which makes them liable to go under heavy strain. I think Neptronix properly sheared his cover whereas mine was still working but the screws had gouged the metal.

OP I don't think you will have any problem with the gears. They are very tough.

25kph however is ridiculously slow for a Velomobile. I would go with 10 turn instead and go for the temperature probe option. A three speed switch should take care of climbing issues. On the flat a fit cyclist can maintain 60kph on a velo for significant periods of time.

Remember, the motor and the battery will probably add an extra ten kg to the weight so you have to have something to offset the handicap. There are other people from Switzerland on the forum perhaps you could canvass their opinions on the matter. Just put Swiss or Switzerland in the title and I'm sure they will respond.
 
dodjob said:
Anyway, a 12T mac is REALLY a torque motor. You don't have any fear to get about getting hot if you keep it under 25Km/h really nothing, even completely loaded (I used them for cargo bikes in Germany). The new gearing is also very strong.. nothing to fear again.

What about going 5-10kmh up a very steep incline? I imagine there is too much to fear.
 
What I want to see is 12T Mac on a 20 inch rim fed with 120V lipo. Wonder what kind of speed and power you will get.
 
I just took delivery of a MAC 12T motor from em3ev and I was wondering if someone could tell me what the white wire is for on the 6 pin hall sensor connector from the motor?
 
I ran a 12T for about 1000 miles at 40A, followed by about 1200 miles @ 30A, and another 500 miles @ 15A. No problems so far.

At 40A it will utter some potentially self destructive sounds with an zero ramp controller that snapped to full throttle from a stop.

At 40 amps (52V) it would push my 270 lb gross wt up a 9% incline continuous for 2 miles while maintaining 20 MPH average. It will climb 16% grades with a slight groan seen in the video at the bottom of the page on the link below.
http://www.triketech.com/Drivetrain/PowerAssist/HPV-MAC.html

It now runs on a 36V (40V Peak) 15A peak on my wife's FS26, top speed is about 20 MPH. I currently have a 10T @ 30A.
 
Yes, I know this is an old thread but wanted to add a little info in case anybody comes across it.

I have a 12T MAC and have laced it to everything from a 20" rim to a 27.5/650B rim...if I use it off road, it overheats. It is because I am not spinning the motor fast enough to keep it in the efficient rpm range. The only way to change the gearing of an internally geared hub motor or a non geared hub motor is by changing the diameter of the wheel it is in. Well unless you mount it and use it like a mid drive motor :).

The 12T MAC with a 14s battery will run about 25 mph when mounted in a 27.5/650B wheel and about 20 mph when mounted in a 20" wheel. The more you can run it with the throttle wide open i.e. at the peak rpm, the more efficient and cooler the motor will run.

My recommendation is to use the 12T MAC for pavement with some very moderate hills. If you live where it is flat, the 10T motor works well. IF you want to go slower than the speeds I outlined above and/or you want to ride off road, I'd suggest a BBSHD...you can change the gearing with the sprocket on the motor and/or the cog on the rear wheel and get much better efficiency at slower speeds.

Spinningmagnets makes great points in his post above...IMO he words it way too nicely, so pay close attention to his comments :).
 
Back to the Original topic. 12t mac will work, but if you want to run 40 amps, get a direct drive motor of any kind. Sheds the heat better.

But because of weight, a way smaller wattage would be a bad idea too.

Macs or other motors of that type have a good track record of standing 30 amps of 48v. Also, all the shit you read is not talking about heavy weights up steep hills. 400 pounds total weight, and 1000w up a steep hill will melt a mac, if the hill is long. So a mac may limit the mountains you can go up.

A low rpm DD motor would be better for you, especially in 26" wheel.


To mlv. that would be fun, for about 5 -10 miles, then it would melt. 10 miles of that will also melt a 500w size DD. As I found out at the races. Do go ahead and do it though, melting motors is great fun.
 
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