best hub motor

Electric Motors and Controllers

best hub motor

Postby mbs » Tue Sep 25, 2012 10:36 pm

i'm wondering if you guys have any suggestions or any idea of the best hub motor today?
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Re: best hub motor

Postby DAND214 » Tue Sep 25, 2012 10:44 pm

the best one is the one that works for your needs.

we need more info.

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Re: best hub motor

Postby amberwolf » Wed Sep 26, 2012 3:35 am

mbs wrote:i'm wondering if you guys have any suggestions or any idea of the best hub motor today?

No such thing.

Best for what?
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Re: best hub motor

Postby arkmundi » Wed Sep 26, 2012 4:16 am

Research on hub motors is the best start for an ebike project. After doing my own research on the topic, I chose the Heinzmann 500 watt front hub. If you haven't already, I'd suggest reading:
http://en.wikipedia.org/wiki/Electric_assist_bicycle
Federal law in the United States states that an electric bicycle must have a top speed when powered solely by the motor under 20 mph (32 km/h) and a motor which produces less than 750 W (1.01 hp).

So, where you live and the laws of the road must be accounted for. I recommend being street legal, which means in most places, a low-power, low-speed electric assist and not a "motorized bicycle." If that's what you want, then just buy one of those so it can be registered, have all the safety equipment, etc.
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Re: best hub motor

Postby amberwolf » Wed Sep 26, 2012 4:45 am

That's not federal law restricting all ebikes. That's the federal CPSC regulations about what can be manufactured and sold as an (low powered) ebike (for use on public roads).

People keep posting that up as if it was "the law". :( it's not. Each state and locality has different ones.
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Re: best hub motor

Postby arkmundi » Wed Sep 26, 2012 4:54 am

amberwolf wrote:That's not federal law restricting all ebikes. That's the federal CPSC regulations about what can be manufactured and sold as an (low powered) ebike (for use on public roads).

People keep posting that up as if it was "the law". :( it's not. Each state and locality has different ones.

Hope I don't have to test that in the courts here. There's much that could be written about this. My case, should it happen, can be substantiated. Ultimately, its case law that matters and not the laws as interpretted by local law enforcement. There must be a distiction between "electric assist" and "motorized bicycle." This provided that, as part of federal consumer protection. Gaia help me if I have to navigate having to register my ebike as the latter, an eventuality that would lead to either having to abandon the ebike or be an out-law. :x
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Re: best hub motor

Postby mbs » Wed Sep 26, 2012 10:14 am

the best direct drive hub motor in terms of efficiency(base on its efficiency curve). i'm trying to build my own ebike right now and if it's not too much to ask, i'm wondering if you guys do know or can suggest other direct drive hub motor that has a great efficiency.
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Re: best hub motor

Postby Jeremy Harris » Wed Sep 26, 2012 10:48 am

mbs wrote:the best direct drive hub motor in terms of efficiency(base on its efficiency curve). i'm trying to build my own ebike right now and if it's not too much to ask, i'm wondering if you guys do know or can suggest other direct drive hub motor that has a great efficiency.


Again, it depends entirely on what you're going to do with it.

We need more information, I'm afraid.

- The size of the wheel you're going to fit the motor into has a massive effect (because diameter determines motor torque and motor torque is directly proportional to current and current is the single biggest driver when it comes to motor efficiency).

- The total weight of the bike and yourself (because weight determines the power needed to climb hills and accelerate and so also the torque requirement and hence the current and efficiency, as above).

- The maximum speed on the level that you want to go (because speed determines rpm and rpm is determined by the motor velocity constant and battery voltage, and the velocity constant is determined by the motor winding, which has a direct impact on motor resistance and hence efficiency at any given torque).

The simulator on the Grin web site, here: http://ebikes.ca/simulator/ is a really good starting point to play "what ifs" with, and may help you understand how efficiency varies a great deal with load.
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Re: best hub motor

Postby mbs » Wed Sep 26, 2012 7:42 pm

Jeremy Harris wrote:
mbs wrote:the best direct drive hub motor in terms of efficiency(base on its efficiency curve). i'm trying to build my own ebike right now and if it's not too much to ask, i'm wondering if you guys do know or can suggest other direct drive hub motor that has a great efficiency.


Again, it depends entirely on what you're going to do with it.

We need more information, I'm afraid.

- The size of the wheel you're going to fit the motor into has a massive effect (because diameter determines motor torque and motor torque is directly proportional to current and current is the single biggest driver when it comes to motor efficiency).

- The total weight of the bike and yourself (because weight determines the power needed to climb hills and accelerate and so also the torque requirement and hence the current and efficiency, as above).

- The maximum speed on the level that you want to go (because speed determines rpm and rpm is determined by the motor velocity constant and battery voltage, and the velocity constant is determined by the motor winding, which has a direct impact on motor resistance and hence efficiency at any given torque).

The simulator on the Grin web site, here: http://ebikes.ca/simulator/ is a really good starting point to play "what ifs" with, and may help you understand how efficiency varies a great deal with load.



yes! i'm currently looking for a 20 inch diameter, and operated at 48v. i did already look at their site before, it seems that 9c 2807 would already fit my ebike project but i'm still in search for a better motor(efficiency curve) right now.
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Re: best hub motor

Postby Jeremy Harris » Thu Sep 27, 2012 1:45 am

mbs wrote:yes! i'm currently looking for a 20 inch diameter, and operated at 48v. i did already look at their site before, it seems that 9c 2807 would already fit my ebike project but i'm still in search for a better motor(efficiency curve) right now.


OK, we're slowly getting there................

Again, what's the total weight and cruising speed that you're looking for?

As I tried to explain above, motor efficiency is very highly dependent on load. A motor winding choice that gives good efficiency at one rpm and load will likely give poorer efficiency at another speed and load, it's an inherent property of all permanent magnet motors.

For example, say you decide on a 9C 2807, as you suggest. This will be around 84% efficient when running at about 22 mph on 48V with a 40A current limit controller with decent FETs. If you intend to cruise at around 22mph then this would be a reasonable choice. If you cruise at around 15mph (about 60% throttle), then the efficiency comes down to around 82%, which is still reasonably good.

If you want more speed, then look at the lower winding count motors. For example, sticking with the 9C range, a 2805 could give you around 84 to 85% efficiency at around 30mph, but as with the 2807 efficiency will drop off at lower speeds. For example, at 15mph the efficiency would be down to about 80% (around 45% throttle).

As said before, there is no "best" motor, only the best compromise for the particular way you want to ride.
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Re: best hub motor

Postby Kingfish » Thu Sep 27, 2012 11:11 am

Just a small note:
If you pedal with the motor, also consider at what speed you are most comfortable at maintaining together. I found that my 2806 could take me to 35-36 mph easy enough, but it was really pushing me hard to stay at that level – even with the mods to the drivetrain (53-11). It’s funny cos the AveS difference between my 2010 FWD road trip and the 2011 2WD road trip is about 1 mph gain at best; it just goes to show that I felt comfortable cruising at about 28-30 mph which is close to optimum for that series of hub motors.

When facing stiff headwind, I dropped gear and speed to 23 mph so as to extend the range, however this makes for a long day in the saddle.

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