Electric Motor Without Controller

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kwest
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Electric Motor Without Controller

Is it possible to run an electric motor without a controller? Perhaps through the use of a relay? What would the implications of this be?

Thank you!

Reid250
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Re: Electric Motor Without Controller

Yes, golf carts have been doing it with switches or solenoids for 40+ years. 99.9% of the electric motors in the world run without a controller. I think you are referring to some sort of a scoot by being here, so the better answer might be that the controller serves a very important function of adjusting your speed smoothly. The old golf carts had 4-6 speeds with a fair jerk as you changed speeds. The lighter the vehicle, the more pronounced the jerk would be. The controller for a hubmotor provides much more sophisticated manipulations of current and voltage for speed and torque, than needed for a conventional electric motor.

What do you have in mind? Have you Googled electric motorcycle or looked here? http://www.instructables.com/id/How-to-build-a-72Volt-electric-motorcycle/

kwest
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Re: Electric Motor Without Controller

Sorry, yes, I was just in the process of revising my post to include more information.

I'm building a power assist for my commuter bicycle with a hub motor. I have a long flat commute with a couple very long straight sections where I would like to increase my top speed. I do not plan to use the assist in acceleration or cruising below 25km/hr (15mph), it is only the top speed and resulting time savings that I'm looking for. I'm also trying to build a light, simple, bare-bones system that will meet those needs, and I have begun to think that I may not need the added complexity of a controller.

The motor I'm considering using is the BMC V2 (high speed, front hub). Would it be possible to run that motor without a controller? I'd like to set it up so that when I flip it on it will output a predetermined amount of throttle. I assume there will be a jerk as it gets turned on, but probably nothing I can't handle. Can you think of any other implications?

Thanks,
Kellen

bnorthup
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Re: Electric Motor Without Controller

I have my electric bike setup with just a toggle switch so that it is either on or off. I have had a total of 6 electric bikes and I like this method better than the controller where you have a throttle. You must have a brushed motor to do this though, because the brushless motors are actually a dc motor where the controller takes the dc from the battery and makes it into a three phase alternating current that goes to the front hub. The brushless motors have three wires going into the hub motor. The brushed motors just have two wires going into the hub. I love the brushed motors and I do not care for the brushless motors. I have found that the electric bike community does not agree with me. They all want to have a throttle... I hate having a throttle. It is useless. When I need to slow down I simply use the pedals like a normal bicycle. The brushed motors are cheaper to make but they seem to get hotter in the summer though and now the more complicated brushless motors have completely crowded out the brushed motors and you just can't hardly get the brushed motors anymore... Mine was from Wilderness Energy and it says AOTEMA on the hub. It is a wonderful hub motor. I wish I could get more of these fine brushed BD-36 hub motors.

kwest
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Re: Electric Motor Without Controller

So I guess the answer to my question is that if I'm using a brushless motor, I will have to use a controller, there is no way around it!

The thing about the controller is that they are all so overbuilt with features I don't want. Look at this photo:

There's regenerative braking, motor reverse, analytic device, etc... all built in. I don't need/want any of these things and I feel like they will just increase the probability of having things go wrong. And it's just more stuff to carry that I don't need to be carrying. I just want to build the most basic and robust setup possible to just have a small high speed assist on my bike.

Would there be a simpler device that will allow me to use a brushless motor in a simpler fashion?

Thank you,
Kellen

bnorthup
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Re: Electric Motor Without Controller

Tell me about it...... I have felt this way for about 5 years. Who wants all that useless stuff? It almost seems as if this is all designed to increase the price of the electric bike. The worst part is that you almost can't get the simple brushed hub motor anymore. There are certain advantages to the brushless motor and this is why everybody has gone to them... Cost and simplicity are not the the reasons. They don't want you to have a brushed motor because you MIGHT have to change brushes after 5,000 miles and because everybody knows that some individual will undoubtably manage to get into a jam when the bike is stuck at full power. Liability is why you have to have a throttle.
Even with the brushed motors, they still come with a controller. I did some tests and could not find any noticeable loss of power or voltage through the controller but the controller was something that you had to keep dry and it caused a snarl of wires that you had to deal with. Many connections had to be shorted together to even make the thing work at all.
There is a toggle switch that Home Depot and Lowes sells for $5 that works just fine for electric bikes where you might have a current spike up to 60 amps briefly but most of the time you are running at about 15 amps.

kwest
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Re: Electric Motor Without Controller

I'm glad you agree and that I have some support in this issue. However, I have still yet to see any sort of solution. Can anybody think of a simpler way to run a brushless motor? Perhaps a very simple rudimentary controller that performs just the basic functions necessary to make the motor run. Even if it's just an on/off operation.

Thanks!
Kellen

wookey
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Re: Electric Motor Without Controller

You could make a circuit to drive a brushless motor that did nothing other that drive it at full speed but it wouldn't actually be much simpler than the fancy controller. Most of those extra features come pretty-much for free given the basic design.

It's easy to use a brushless motor without a throttle, bnorthrup - just replace it with a switch - so you get a two-position throttle: full and zero.

My understanding was that brushless motors are a lot more efficient than brushed motors. That's got to be worth somethig hasn't it? Saves on either weight or battery cost, and is a big part of the reason why brushed motors are dying out.

Wookey
Sakura s50 (Efun A)

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