Newbie wants to know, which are more suitable for building a E Bike ?

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pengyou
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Joined: 06/17/2007
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I have read many articles in the handbooks and most of them dwell on batteries, or controllers or some other aspect but I did not find one that dwelt specifically on motors. I see pictures of home done conversions but there is seldom detail on why they choose the motor they choose, what makes it good etc.

I know virtually nothing about electric motors - now I know a lot more about controllers and batteries :)

For example:

what kind of motor is suitable? Which ones are more suitable? Which technologies are most suitable? what kinds of words describe them? How are motors rated? i have heard some people say that, for example, motor A is rated at 250 watts at 24 volts but if you use 48 volts it will produce 500 watts. Actually I am a complete moron on this topic.

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reikiman
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Re: Newbie wants to know, which are more suitable for building

This should get redirected to the forums.

The ratings you discuss are maximums .. so if you exceed the rating there is a danger of the motor blowing up.

- David Herron, http://davidherron.com/

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Stleride
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Re: Newbie wants to know, which are more suitable for building

` :?

Quote:

This should get redirected to the forums.

I believe it's currently in the Bicycles and Pedelecs.

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abcd
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Re: Newbie wants to know, which are more suitable for building

There are may ways to build an electric motor, it seams that most electric bike designs have used types of PM motors.

Two main types of these brushless and brushed, brushless can be more efficient but costs more and could be less rugged depending on who designed it. In theory a brushless motor should run for a long time, if the controller and motor thermal designs are correct so that the electronics don't fail from over heating or broken controler wiring..

They ussualy select motors with very high power magnets in them, since they have a high power to weight ratio and can produce lots of torque at high efficiency , since the magnets produce their own magnetic fields this improves efficiency and their high torque curves, removes the need for a transmission.

So the ideal electric bike motor needs to be light weight, very energy effecient, as having to add more battery capacity adds weight, that
you must then move , up hills etc.

I think one of the factors for PM motors is startup current, when the motor spins it acts as a generator this voltage limits the current thru the motor. So worst case is motor is heavly loaded so it turns at low rpm , no counter voltage to limit current the motor over heats and burns up either its wiring or its controler electronics in the case.

I think many new controlers limit current to safe levels to prevent this.

PM motors did best at higher rpm, and like lots of current for high torque , this makes for best design for low weight, but is not 266 rpm of a gearless hub motor.

For high torque you need larger wires inside the motor to handle the current, then cooling to get rid of heating from power lost inside the motor.

I kinda like this design my self . http://en.wikipedia.org/wiki/Homopolar_motor

pengyou
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Joined: 06/17/2007
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Re: Newbie wants to know, which are more suitable for building

Thanks! I put this thread in the forums but the moderator moved it here. I think he felt it would get more attention here.

What about the following motors? Would they be useful for an ebike? It would probably be helpful to hear your dialog on these.
2 HP 12-24V DC ELECTRIC VEHICLE MOTOR
Electric Bicycle/Scooter Brushless 24 Volt DC/VDC Motor
Electric Motor DC permanent magnent 24 36 48 volt Etek
Battlebot 350 Watt 24 Volt DC Electric Scooter Motor
Battlebot 350 Watt 24 Volt DC Electric Scooter Motor

abcd
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Re: Newbie wants to know, which are more suitable for building

I would give a simple answer, only one of your motors, came from an electric bike.
"Electric Bicycle/Scooter Brushless 24 Volt DC/VDC Motor"

and is brushless, and includes a built in speed controler.

I would use that one of the motors you list. or two of them if you want more power.

Good value for the price.

Also all the other motors seam to be brushed designs and or needing mega battery power and speed controller.

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