MAC motor + Trek 4300 build

20" Magic Pie update:

I took this thing out for a test spin at 57v nom / 33a. LUKE / METHODS ARE 101% RIGHT!!!!!!!!! a small wheel motor takes off like an effing rocket!!! at just under 2000w peak, this motor accelerates as fast as the MAC motor on 4kW - it just has a lower top speed, that is all.

This is on the stock phase wires, 5AH of 1.5 year old lipo at half charge, and a wimpy controller.
I didn't have a spedometer on the bike i tested, but at 57v nom, i believe i was going about 20-23mph.

I could never get the MXUS to accelerate like this. Not even on >4000w ( 80v/ 56A ).
She'll need 72 volts minimum though.

Perhaps this should branch into another thread soon. The bike with the MAC is still down waiting on grease.. :(..
 
Hi Dave,

Welcome to the magic world of Pie ? haha couldn't resist! :D

It sure is a beast isn't it ? I never found it accelerates as quick as a mac at only 2kw, but maybe in a 20" it makes a difference ?

I always thought it looked strange a 20" at the rear and a 26" at the front, but I guess I'm not used to it!

HAHA turn that beast up to 50 battery and 100 phase on the 12 fet, You might not even need the 18 fet now with the 20" wheel ? :twisted: That's what I'm running in a 26" wheel.

I wouldn't drill those covers Dave, not yet, you'll find that pie will hardly even get warm, unless going up pikes peak of course! But in the 20" it might not be so hard on it!

One thing for sure though is you may go 80-90 volts for any kind of decent speed, are you using the 120% setting ?

I think the trick with these motors is to use volts rather than monster amps and let speed take you up, I know it will probably take 3kw to move you up Pike's Peak at any decent speed, but we all know motors are more efficient at faster rpm ?

I would install a temp sensor just in case!

Time for new thread ? :mrgreen:
 
I found that riding a large tire, 1.5" diameter larger killed my acceleration on my 6 turn Mac. It makes me want to get a 1" tire just to see how much more torque I can see with it. If I ever end up ruining this wheel, I'll rebuild the 6 turn in a 24" rim.

This really makes me feel like I'm just missing out on so much better performance since I never run can run this wheel at max speed with its low current.

Volt up gear down as is said on ES....
 
Neptronix, how many kgs does the wheel with a magic pie and tire weights?

How does the bike feel with 20" rear wheel and 26 front wheel?
 
gensem said:
Neptronix, how many kgs does the wheel with a magic pie and tire weights?

How does the bike feel with 20" rear wheel and 26 front wheel?
Click to expand...

16 pounds without the tire, so ~7.25kg.
So yeah, it's up there. I think the Crystalyte HS weighs the same.
 
neptronix said:
So yeah, it's up there. I think the Crystalyte HS weighs the same.
Click to expand...

Good weight... how is the bicycle geometry with a 20" back wheel and 26 front wheel?
Is the pedal hitting the ground, or there is still clearance?
 
Thought I'd revive this thread to ask David a question seeing as he seems to know the limits of the MAC motor. I've just got my mits on an 8T in a 20" wheel that I want to see how far I can push it. I plan to put it on the KMX and run it from a Hua Tong controller on 18S, in your experience how much can you push it before something melts and what is going to go first?
 
All right, will make sure i get my fat commision check from cell_man :lol:
GMU - if you have a flat area and do some pedaling, you will totally love the 6T. I'm glad i could be of help anyway :)

Tom: on a 20" wheel, the MAC needs some higher volts to get the same speed as 26" for sure.. I think your experience will be the same as when i run my 8T on 15S - takes a very long time to get hot, good top speed, and very good acceleration.

I don't know anything about the hua tong controllers, but this motor does have some special needs when it comes to controllers. Only controller i can really recommend is cell_man's unit, some have said Lyen controllers work OK but it is hit or miss.
 
As for this bike, it's been turned into a pedal bike for the time being. I am still waiting on motor grease and a programming cable from cell_man. Never order via sea shipping, especially near Chinese new year.

I installed an RST Gila fork on it the other day. Now i've never ridden a bike with a non worn-out suspension fork before, so this is a blast! makes pedaling around these awful streets liveable.
 
GMUseless said:
Allright Nep: you sold another one. Just ordered me a 6T from cell_man. Thanks again for sharing all your MAC experience.
Click to expand...


Welcome to the club. I found that my 6 turn came alive once I gave it 1000watts. Anything under is not worth it. The difference between 800 and 1000w seems really big for some reason. Now my torque arms are showing wear.
 
What would you say is the comfortable limit for the MAC? I've got a few 8T and a 6T and a lyen 12 fet on the way. at 18S how many amps can you put through it (not continuous, in bursts, before gears turn to peanut butter and windings start to cook? At the moment I'm running my 10T on 1700W max, it only ever pulls that when going up hills, full speed cruise is 800W tops and it seems to handle that fine (on 12s) how high is too high?
 
That depends on many factors. I melted my halls and phase wires at 15S (62V) and 56A max. That's on a heavy DH bike with a heavy rider (220lbs).

Took 15 minutes.

I've rebuilt the motor and am throwing a CA on as well as a new controller to drop the amps- I'm about to start testing it again at various amps and see how it fares. I installed a temp sensor inside the hub as well so should be able to get some decent results.

I know that Dave has run his MAC at similar power levels to me without a drama- but not sure what his loaded rig weighs!
 
I'd say 2kW is right around what it likes for about an hour. I used to say 2.5kW, but throw in some seriously steep hills or hot weather and you may be crossing into the danger zone.

4kW would have melted my motor in short time. Good thing i only ran it for 5-10 mins, tops at that power. Otherwise i ran at 2.3-2.6kW.. no problems.. mostly flat.. mildly hilly land, and lots of pedaling, especially during acceleration.

Some people have had problems with halls, i guess i have just been lucky. I'm 230lb and usually run a 12lb lipo pack on a mid-level hardtail bike.. not super light.. :) The difference may be in the pedaling. 50T in the front, 11T in the rear.. so the acceleration spurts may have 100-200w of human power added.
 
Depends on your wind. You do have to feed the motor the appropriate amount of amps for whatever speed you're going.

You wouldn't want to run 76v/20S nominal on an 8T for example and feed it 30 amps. You'd need about 60+ amps at the top speed that voltage can produce, so you'd just be wasting energy if you hit full throttle, running at way below 80% your unloaded speed.

For the 8T, i like 36A-40A on 57-60V nominal ( 15S or 16S lipo equivalent ). That's where you're riding the edge of failure.

For the 10T, something like 76v/30A would be more appropriate as it likes more volts than amps due to the speed of the winding.

For the 6T, 48v is almost maxing it out and you need to feed it tons of amps to maintain the crusing speed, unless you are veloman and are pedaling like a manimal on a road bike, hehe.

These figures are all for 26" wheels BTW, so a different size will skew the results of course. On a 20" wheel, you might wanna jump up about 2T to get the same results as a 26" wheel ( just an approximation. )

To be honest, these motors aren't good for more than about 35mph / 56kph constant if you want them to last. Seems that the clutch and hall sensors are still weak points. The upside is that they will go before the stator. You can burst to higher speeds, but something will break eventually. 35mph is around 2kW.

Can't wait to see how the new stators perform. Am anxiously awaiting a new 10T stator to run on 20S/76v over here... :)
 
stripedtuna said:
Awesome.. thanks for that info mate..

I am getting the 8T, with the 52V A123 battery. So all that info will certainly help me set a good safe max current limit..

cheers.
Click to expand...

That's a good choice. I think the 6t should be for 24 or 20" wheels, or someone who will not add voltage, just amps. Or it'd do great in a recumbent hauling a$$. My 6t rides good now that I am over 1000w, but I still never go near it's proper rpm on 48v which is near 40mph for two reasons: it's insanely inefficient to go that fast, I don't need to, and I limited it to 23amps or so. Efficiency still seems good.

I would guess that the gears would wear out quicker on the higher turn motors, all other things being equal. Of course, that's not a reason to get a 6 turn unless you hate accelerating well and run low power.
 
Guys...............
Never do China to USA via surface mail if you need it within 3 months...

Been a bit over two months and my grease for the MAC motor, programming cable, and a motor for 'Tom Tom' are still on the boat :evil:

SAL on the other hand, gets here in about a week or week and a half!...

So i want to get the damn MAC motor running again... any suggestions on what motor grease i could substitute?
I'm thinking white lithium grease might be good?
 
Red lithium grease is what is used in the TongXin motors (and what I replaced the orignal with when I redid mine), and also what I will be using in one of my Fusins when I redo the grease in there (assuming I don't just try an oil bath). I forget what was in the Fusin originally, but I think it was yellow.

I think there are pics of the can including it's brand/etc in my TongXin thread. If not, I can go look for the info on the can later.
 
Thanks amberwolf, however i just ordered some, lol.

http://www.ebikessf.com/technical/bmc-motors-faq[url][/url]
ebikes sf mentioned that BMC specified mobilgrease 28.

So i ordered a 2lb tub of it and plan to resell small packages of the rest. $30 shipped and all i needed was maybe 3oz :|. Oh well.

Your tongxin uses these weird metal rollers that may very well have a different grease specified for them.
Plastic and plastic composites require different stuff.
 
Hi! I've just recently becoming interested in building myself an ebike.
I'm looking at the MAC motors from cellman and I saw your videos earlier in this thread.

I want my motor to be as silent as possible. When freewheeling it makes a fast clicking sound, is this from the motor or the freewheel kit? If it's the freewheel kit, are there any more silent ones out there?

The kit from cellman includes e-brakes, is this for cutting the power to the motor when I hit the breakes? If so, does that mean I have to use these included breaks? Because my gear shifters on my bike is in one package with the brakes, then I must replace the gear shifters too, I guess or?

Thanks!
A
 
Yeah, i've got a shitty DNP freewheel, which definitely makes some noise when being broken in. You'll notice that sound disappears later on. It's a fairly loud clicker too. A shimano megarange ( hard to find!! ) with a 11t low gear would be better.. start hunting on eBay!

You're right about the brake levers. You don't have to use them though. I don't.
You'll probably end up removing your front deraileur & front shifter anyways and go to a big single speed chainring. So it wouldn't be hard to use one of the brake levers as an emergency cutoff.

tidelipop said:
Hi! I've just recently becoming interested in building myself an ebike.
I'm looking at the MAC motors from cellman and I saw your videos earlier in this thread.

I want my motor to be as silent as possible. When freewheeling it makes a fast clicking sound, is this from the motor or the freewheel kit? If it's the freewheel kit, are there any more silent ones out there?

The kit from cellman includes e-brakes, is this for cutting the power to the motor when I hit the breakes? If so, does that mean I have to use these included breaks? Because my gear shifters on my bike is in one package with the brakes, then I must replace the gear shifters too, I guess or?

Thanks!
A
Click to expand...
 
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