12t 10t 8t etc

[michael.i@me.com]

Can anyone give me a good detailed explanation on how the number of turns relates to motor characteristics?

I am just a little confused on why someone would want more or less turns in their motor.

I am looking at buying a Mac geared motor for my full size mtb and have been talking to cell man via email and he is recommending to me a 12 or 10 T motor.

http://www.emissions-free.com/catalog/i24.html

Am I correct in thinking that more turns means stronger motor? What I really want is something that gives me power for trails and hills. I don't really need high speed on this bike, just want hill climbing. I am 255 lbs. I bought a 1000watt direct drive motor for my bike and am not happy with the power I am getting from it. I am not sure how many turns the 1000 w motor has.

Maybe when I have time I will take it off the bike and open it up and have a peekaboo. but I need some time to do this, and time is precious at the moment.

Thanks in advance for your help and suggestions.

One more thing, does anyone know if this motor supports regeneration or does it freewheel?

 

[neptronix]

more turns = slower speed per volt.
less turns = more speed per volt.

This applies to all motors.

8T is a nice balance of all attributes :]

It's believed that a slower ( per volt ) motor will give you better torque, but that's up for debate. I think if you put an equal amount of wattage into one motor VS another, you may very well end up producing the same power/torque.

 

[michael.i@me.com]

more turns = slower speed per volt.
less turns = more speed per volt.

This applies to all motors.

8T is a nice balance of all attributes :]

It's believed that a slower ( per volt ) motor will give you better torque, but that's up for debate. I think if you put an equal amount of wattage into one motor VS another, you may very well end up producing the same power/torque.

Why is this up for debate? Hasn't anyone tested this before? I can't be the first one asking a question like this.

 

[Miles]

Why is this up for debate? Hasn't anyone tested this before? I can't be the first one asking a question like this.

It's only up for debate among the wilfully clueless. A motor's torque constant (torque per amp) is the reciprocal of its velocity constant (angular velocity per volt).

If you double the number of turns you halve the velocity constant and double the torque constant.

 

[michael.i@me.com]

Why is this up for debate? Hasn't anyone tested this before? I can't be the first one asking a question like this.

It's only up for debate among the wilfully clueless. A motor's torque constant (torque per amp) is the reciprocal of its velocity constant (angular velocity per volt).

If you double the number of turns you halve the velocity constant and double the torque constant.

Soooooooo more turns means more torque? And that means better hill climbing power?

 

[neptronix]

The only thing up for debate is that a lower speed winding will produce more torque, ultimately.

I don't think anyone has tested it formally to this day ( like for example, on a dyno )

 

[Miles]

Soooooooo more turns means more torque? And that means better hill climbing power?

Nope. It just means more torque per amp. More turns means greater resistance. The number of turns doesn't affect the efficiency. The amount of heat generated for a given torque remains the same.

 

[michael.i@me.com]

Soooooooo more turns means more torque? And that means better hill climbing power?

Nope. It just means more torque per amp. More turns means greater resistance. The number of turns doesn't affect the efficiency. The amount of heat generated for a given torque remains the same.

Sorry if I seem to be asking the same question over and over, but if I am buying a hub motor for my bike, and I have the option of more or less turns, and my objective is hill climbing power over higher speed, should I be ordering one with more or less turns?

I a, assuming that this is why they offer the option, however I am not clear on this.

Thanks in advance...

 

[Jeremy Harris]

It's only up for debate among the wilfully clueless. A motor's torque constant (torque per amp) is the reciprocal of its velocity constant (angular velocity per volt).

If you double the number of turns you halve the velocity constant and double the torque constant.

You need to talk to wesnewell, Miles, he'll put you straight on just how wrong you are........................ :wink:

 

[michael.i@me.com]

Omg why can't this be simple? Lol

I just want a hill climber lol

 

[Miles]

The only thing up for debate is that a lower speed winding will produce more torque, ultimately.

I don't think anyone has tested it formally to this day ( like for example, on a dyno )

What do you mean by "producing more torque"? If you mean "less heat for a given torque", then it won't. A PM motor will draw enough amps in order for the torque to balance the load.

 

[Jeremy Harris]

Sorry if I seem to be asking the same question over and over, but if I am buying a hub motor for my bike, and I have the option of more or less turns, and my objective is hill climbing power over higher speed, should I be ordering one with more or less turns?

I a, assuming that this is why they offer the option, however I am not clear on this.

Thanks in advance...

You need to match your power requirement, speed requirement and wheel size when choosing a motor. The simulator here: http://ebikes.ca/simulator/ is a good place to start, as you can try different motor, wheel, battery and controller combinations and see roughly how efficient each may be.

There are some general rules with hub motors that might help. Motors have a velocity constant, Kv, that determines how fast they will turn for a given voltage. The higher this number, the faster the motor will turn for a given voltage, so for a small wheel bike it's better to use a high Kv motor to reach a given speed, for a big wheel bike it's better to use a lower Kv motor to reach that speed. The Kv often isn't quoted, but the smaller the number of turns the higher the Kv, and vice versa.

The maximum power that the motor can deliver at a given battery voltage is also related to the Kv and hence the number of turns, because the greater the number of turns, the greater the motor winding resistance and the lower its ability to handle high current without overheating.

If you start off by estimating the total weight of you and your bike, deciding on the battery voltage and capacity you want/can afford and decide the speed you want to be able to go on the flat, then you can just try some different motors and controllers on the simulator and see what best suits you.

 

[Miles]

You need to talk to wesnewell, Miles, he'll put you straight on just how wrong you are........................ :wink:

I'm staying well clear.... Shades of a similar "debate" on the PowerAssist group?

 

[neptronix]

Sorry if I seem to be asking the same question over and over, but if I am buying a hub motor for my bike, and I have the option of more or less turns, and my objective is hill climbing power over higher speed, should I be ordering one with more or less turns?

Here's the thing. When you change the winding, you change what ratio of voltage to amperes are needed to make a certain amount of power.

AFAIK, that's the only difference.
So, a 10T on 48v / 20A would perform very similarly to an 8T on 36v / 30A.

The MAC motor, regardless of the winding, can only push so much watts continuously. A 10T on 36V might be the best because it goes at a slower speed, meaning that there is less aero drag going up the hill, reducing the load and increasing the efficiency. That would be the only factor i can think of that would cause it to do a better job.

Clear as mud?
Hey, i told you you were opening a can of worms.. :lol: :lol:

 

[neptronix]

BTW, a MAC is a good climbing motor. But a big DD in a tiny wheel is better. Sorry to change the subject, but what kind of hills are we talking? ones that you couldn't normally pedal up?

 

[michael.i@me.com]

BTW, a MAC is a good climbing motor. But a big DD in a tiny wheel is better. Sorry to change the subject, but what kind of hills are we talking? ones that you couldn't normally pedal up?

No nothing stupid crazy or anything.

I have two bikes I ride. One is my "commuter bike" that I have talked about quite a bit on Ed already http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=41512 and I use it for my speedy little trips around town. That bike has road tires and no suspension. SO I dont take it off road.

The motor I have on my twentie is the exact same one I have on my 26" mtb now, but it performs like crap on the bigger wheel. So I asked around and it was suggested to me that I obtain a Mac motor for the 26" mtb as it would offer me the slower hill climbing power I desire. Once I was ready to order said Mac moor tho, he asked how many turns I wanted in my motor, and that threw a stick in my spikes so to speak. This is where this all started.

I don't need speed on my mtb, I just want to have a motor that can haul my ass around on the trails and up the hills in my area. This is all. I have a backpack with a 48v 20ah lifepo already that I want to use with my mtb also.

I believe that these are all my variables. I just want someone to advise me on the issue of turns in my new Mac motor.

 

[neptronix]

Ahh.. i see your other build.. you've got a mid size DD in a 20" wheel - that's a great climbing setup!. It may be a better climber than a MAC in a 26" wheel actually, FYI.

If speed is not important, go with the 10T then. You'll hit maybe 25mph on that 48v battery pack. similar to the speed with your other bike.

'cept you won't look as silly on it with a 26" wheeled MTB ;]

 

[1000w]

Hey Michael,
I have used a 8, 10, and 12 turn Mac.
If you run a 48volt system, which I recommend as a good minimum voltage level to keep the amps down, in a 26" wheel you will get around 52kmh from a 8turn, around 40kmh from a 10turn and around 32kmh from a 12turn.
You are fairly big at 255lb so I would follow Cellmans advice and run a 10 or 12 turn and lean towards the 12turn if 32 kmh is enough for you, because this will give you the pull you will need for the hill climbing you mention.
Cheers,
Matt.

 

[michael.i@me.com]

Ahh.. i see your other build.. you've got a mid size DD in a 20" wheel - that's a great climbing setup!. It may be a better climber than a MAC in a 26" wheel actually, FYI.

If speed is not important, go with the 10T then. You'll hit maybe 25mph on that 48v battery pack. similar to the speed with your other bike.

'cept you won't look as silly on it with a 26" wheeled MTB ;]

Tyvm

 

[michael.i@me.com]

Hey Michael,
I have used a 8, 10, and 12 turn Mac.
If you run a 48volt system, which I recommend as a good minimum voltage level to keep the amps down, in a 26" wheel you will get around 52kmh from a 8turn, around 40kmh from a 10turn and around 32kmh from a 12turn.
You are fairly big at 255lb so I would follow Cellmans advice and run a 10 or 12 turn and lean towards the 12turn if 32 kmh is enough for you, because this will give you the pull you will need for the hill climbing you mention.
Cheers,
Matt.

Awesome. 12T it is then. Cheers.

 

[Lebowski]

Hey Michael,
I have used a 8, 10, and 12 turn Mac.
If you run a 48volt system, which I recommend as a good minimum voltage level to keep the amps down, in a 26" wheel you will get around 52kmh from a 8turn, around 40kmh from a 10turn and around 32kmh from a 12turn.
You are fairly big at 255lb so I would follow Cellmans advice and run a 10 or 12 turn and lean towards the 12turn if 32 kmh is enough for you, because this will give you the pull you will need for the hill climbing you mention.
Cheers,
Matt.

Awesome. 12T it is then. Cheers.

I would also go with the 12T. It gives you the hill climbing you want and if you want more speed than 32kmh, up the battery to 96V for > 50 kmh

 

[Jeremy Harris]

Another confirmation that this would be a good choice for your weight, speed and hill climbing requirement, with the battery that you've already got.

 

[Timma2500]

12t = Good choice for your requirements


Paul

 

[Spacey]

Bottom line for an easy to understand explanation:

6 turn Mac is going to go silly fast but feel like an 80pound weakling is peddling i.e crap on hills and you better have a powerful controller and battery to supply it with the needed amps to get to it's fastest speed. It is great though for small wheels and can go stupidly quick if you have the amps/battery to chuck at it..

12 turn Mac is going to pull trees out of the ground albeit at a much slower pace, pump more volts into it to get the higher speeds.

8T on 48v A123 battery pack still pulls like a train and is good for 33mph on the flat. My next build will have a 10 turn Mac @ 48v

 

[Jeremy Harris]

Out of interest, does anyone know what the BMC versions described on Justin's simulator are WRT to the MAC? I'm guessing that the MAC and BMC have pretty much the same geometry and reduction ratio, so the performance of the two should be similar in terms of getting an estimate for each wind. The simulator just lists the BMC V1, the BMC V2 speed and the BMC V2 torque, so I'm guessing that the torque version might be the 12T, and the speed might be the 8T, but it would be nice to have some confirmation, or otherwise.