# Two motors???



## Davisho (Oct 15, 2021)

Hello out there,
So what is the purpose of coupling two motors together?
And is it best for AC or DC, can they be different from each other?
Thanks for any help.


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## brian_ (Feb 7, 2017)

Two motors are coupled when the builder can't find one motor of the desired size, or can't find one controller big enough to drive the desired size of single motor. There is no other rational reason to use to coupled motors.

Coupling dissimilar motors seems like a good way to get the disadvantages of both motor types without the advantages of either. 

It is normally done with brushed DC series-wound motors because that's the type that people can find and what they can find is not big enough. There are some "pancake" format motors (large in diameter and short in shaft length) that are stacked up when more power is wanted because the internal design of the motor is not suited to making a larger motor of the same diameter (e.g. the ridiculous stacks of YASA motors - four in the back and three in the front - in the silly Mustang Mach-E 1400 project).


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## Davisho (Oct 15, 2021)

brian_ said:


> Two motors are coupled when the builder can't find one motor of the desired size, or can't find one controller big enough to drive the desired size of single motor. There is no other rational reason to use to coupled motors.
> 
> Coupling dissimilar motors seems like a good way to get the disadvantages of both motor types without the advantages of either.
> 
> It is normally done with brushed DC series-wound motors because that's the type that people can find and what they can find is not big enough. There are some "pancake" format motors (large in diameter and short in shaft length) that are stacked up when more power is wanted because the internal design of the motor is not suited to making a larger motor of the same diameter (e.g. the ridiculous stacks of YASA motors - four in the back and three in the front - in the silly Mustang Mach-E 1400 project).


Yes that Mustang is just too crazy we don't need that over kill, it's just we can't afford the big 
9 motor so we are trying to cheaply at least 50 miles an hour and keep the alternator in place to keep the amp hours batteries charged while driving.


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## brian_ (Feb 7, 2017)

Davisho said:


> ... keep the alternator in place to keep the amp hours batteries charged while driving.


What does that mean? "Amp hours batteries" doesn't mean anything. 

Do you mean that you want to run a 12-volt alternator from the drive motor? You can do that, although a DC-to-DC converter is simpler, but it doesn't take much power so you don't need a huge drive motor (or two drive motors).


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## brian_ (Feb 7, 2017)

Davisho said:


> ... it's just we can't afford the big
> 9 motor...


If you are thinking of using two smaller motors instead of one common 9" motor, those two motors plus the two controllers will likely cost more than one properly sized motor and controller.


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## Davisho (Oct 15, 2021)

brian_ said:


> What does that mean? "Amp hours batteries" doesn't mean anything.
> 
> Do you mean that you want to run a 12-volt alternator from the drive motor? You can do that, although a DC-to-DC converter is simpler, but it doesn't take much power so you don't need a huge drive motor (or two drive motors).


Keeping all the batteries in parallel to increase the amperage for longer drive time, but with a motor that gives more than 25 miles an hour.


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## brian_ (Feb 7, 2017)

Davisho said:


> Keeping all the batteries in parallel to increase the amperage for longer drive time...


That doesn't help range. The total energy is what matters; if you put the same battery capacity in a configuration with twice the voltage and half the amp-hour capacity, you would still use energy from it at the same rate (twice the voltage and half the current), and would have the same range.


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## MattsAwesomeStuff (Aug 10, 2017)

Davisho said:


> it's just we can't afford the big 9 motor so we are trying to cheaply at least 50 miles an hour


Whoa, hold up.

You are probably being overly prescriptive in your questions, which might lead to getting the right answers with the wrong context.

Let's start at the beginning.

You're doing a budget build, and are worried about the price of a motor. But you just barely understand motors, and, as above, you misunderstand some critical things about them and are reaching for shortcuts that don't exist.

So, what's your budget, or your budget hopes? What componentry and design choices have you made so far?

It might be that "Oh, just use this motor instead" is your answer, than "this is how to connect two cheaper motors together" that ends up being not cheaper and not actually better.

I'm all aboard with you doing a budget build, it's my preference for projects too, but it doesn't leave room for buying your way out of mistakes if you make any.


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## remy_martian (Feb 4, 2019)

brian_ said:


> Two motors are coupled when the builder can't find one motor of the desired size, or can't find one controller big enough to drive the desired size of single motor. There is no other rational reason to use to coupled motors.
> 
> Coupling dissimilar motors seems like a good way to get the disadvantages of both motor types without the advantages of either.
> 
> It is normally done with brushed DC series-wound motors because that's the type that people can find and what they can find is not big enough. There are some "pancake" format motors (large in diameter and short in shaft length) that are stacked up when more power is wanted because the internal design of the motor is not suited to making a larger motor of the same diameter (e.g. the ridiculous stacks of YASA motors - four in the back and three in the front - in the silly Mustang Mach-E 1400 project).


"Silly"?

Someone's getting old and letting "practical" creep in 😂

Silly gave us Model S in 2012, and later, Silly would give us Ludicrous and Plaid.

An old man gave us the practical Chevy Volt, giving Tesla the runway to be where they are today.

A fully electric Caddy instead of the Volt would've killed Tesla instead of enabling Lutz's abomination to slither into the tech flagship brand to where they're just now going to produce a full-on EV.


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## brian_ (Feb 7, 2017)

remy_martian said:


> "Silly"?
> 
> Someone's getting old and letting "practical" creep in 😂
> 
> Silly gave us Model S in 2012, and later, Silly would give us Ludicrous and Plaid.


You're apparently unfamiliar with the "Ford" (actually contracted out, using no Ford EV tech) Mustang Mach-E 1400. Any Model S, including the Plaid, is efficient and sensible compared to that pile of nonsense. It has seven motors, and seven controllers, and can't even control left-right power distribution... which I suppose doesn't matter when both tires are spinning to make smoke, which is the purpose of this thing.


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## remy_martian (Feb 4, 2019)

COPO Camaro EV was another "silly" siamesed motor setup....through a transmission, no less. GM was all over it for PR...built by a high school teacher & his shop class.


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## brian_ (Feb 7, 2017)

remy_martian said:


> COPO Camaro EV was another "silly" siamesed motor setup....through a transmission, no less. GM was all over it for PR...built by a high school teacher & his shop class.


I agree that the eCOPO Camaro was a nonsensical configuration for an auto manufacturer's product, but at least it only used two stacked motors. The builder is a race team owner... students worked on it, but it wasn't a student project. This is a design that might make sense for some DIY builders, but it would still be more expensive to build than a car which is similarly configured but with one properly sized motor, and less capable than a car with the same two motors driving the rear wheels independently.


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