# Good EV motors?



## Outlander (Sep 11, 2007)

I am finding it very difficult to find electric motors suitable for use in high performance electric vehicles. All the motors I am coming across are general use 25-40HP, etc. Looking for high torque (300-1000ft lbs) and mid HP levels (150-200?) These motors simply don't seem to exist, or cost more than a conversion is worth.

Batteries, easy. Controllers easy. Motors hard.


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## TexomaEV (Jul 26, 2007)

What are you wanting a motor of that size for? Are you converting an armored car? LOL

You can't compare HP between an Electric Motor, and an I.C.E. on a 1to1 scale. 

Just for instance: I'm running a 36volt/400amp Aircraft Starter in my EV. Before I had a controller, I just HAD to do a test drive, so I connected 36 volts to a switch, got in the car, put it in gear and turned on the switch. I ripped out a rubber motor mount, and twisted a CV joint, and spun out the tires. The aircraft starter is rated from 10hp to 30hp depending upon the voltage it is ran at.

I'm currently running the EV at just 78vdc, and it will do highway speeds in just 4th gear. At 36vdc it's only 10hp, at 96vdc it's 30hp, therefore I'm running it mid range of those with just 78vdc.

Lots of people are using 36volt ForkLift motors, at voltages upwards of 120vdc - Some of which have been doing this for over 10 years now on the same motor. I do recommend you build an EV for continuous highway speeds at no less than 96vdc. I'm limited in my voltage level do to the controller I'm using and the state law where I reside at, without becoming a Certified EV Technician. Someday, maybe I'll be able to afford to take the class and test for that certification.


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## Greenflight (Sep 13, 2007)

Hey Texoma, not to be off topic, but I'm just wondering about using lower voltage motors at higher voltage. I mean, it seems like amps would go through the roof! Is it something that actually works?


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## TexomaEV (Jul 26, 2007)

Hi GreenFLight, I'm currently using a 36volt 400amp generator from an airplane engine @ 78vdc nominal. It can handle 96vdc.

I see others out there using 36-48volt forklift motors @ 120+vdc, one gentleman mentioned in a email, he'd been using one now for over 10years this way. 

I believe, the higher the voltage, the lower the amperage needed to perform the same task of the motor. 

Scroll through the: www.evalbum.com , listings and see what others are currently using in the EV's they are driving. This might help.....


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## Greenflight (Sep 13, 2007)

Thanks, this could save me some money!  I guess I've always been a bit skeptic about the use of those kinds of motors in EVs... Sounds like it can work out OK though.

The only thing is, the resistance of the motor doesn't change (unless of course you rewound it) so an increase of voltage should cause an increase in amperage. Maybe the motors are just tough enough to take it.

Does your motor get hot after running for a while? Or does it stay pretty cool? Any cooling fans?


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## veperformance (Aug 17, 2007)

Since you are in the current drain subject , i'm interrested in getting a few statistic from all of you if possible . just a few numbers : your voltage and at different speed the current drain.I want to evaluate power saving with my prototype.you can post or send to my e-mail.Thanks


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## Greenflight (Sep 13, 2007)

Well, my truck has a 120V pack. At 25 mph, it draws maybe 40A or less. At 35 it draws about 80 or 90. At 45-50 (where I do most of my driving) it draws about 130-150. Hope that helps.


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## gromm (Sep 24, 2007)

Greenflight:

Hmm. So 15600-18000 KW? That translates into about 15-18 HP in the real world.

Of course, a gas engine running at highway speed in top gear would be running at only 2500 to 3000 RPM, so it would be putting out relatively few HP itself - just enough to overcome air resistance.


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## gromm (Sep 24, 2007)

TexomaEV said:


> What are you wanting a motor of that size for? Are you converting an armored car? LOL


He *did* say he wanted a high performance car. But then, I heard about this one guy, who welded a JATO rocket to his car...


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## veperformance (Aug 17, 2007)

Thanks for the stats , as for the hp conversion in kw in curious to know how do you take account of motor efficiency ? as a result i'm curious to know what would be the minimum electrical kw necessary to get my 3000lbs transam moving ?just low speed to begin.


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## Greenflight (Sep 13, 2007)

gromm- I got 20-24 hp. Close enough.  It doesn't take much power to keep a car moving... It's getting it moving that takes the juice. When I floor it, my truck will go right up to ~450A (seems to me about 70 hp), and then taper down as it gets up to speed.

ve- I really don't figure in efficiency. I could probably figure about 85%, but I'm really more concerned about the juice coming out of the batteries than the power going to the wheels.

I really can't say what kind of power you'd need for a Transam. If you have a rough guess as far as hp, multiply by 746 to convert to watts. Anybody else done a conversion in that size range?


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## gromm (Sep 24, 2007)

veperformance said:


> as a result i'm curious to know what would be the minimum electrical kw necessary to get my 3000lbs transam moving?


Oh, that's easy. Just calculate the amount of force in Newtons that it takes to push the car 1 meter in 1 second.  Then you have watts.

If you want a bare minimum, consider the fact that you can push the car on your own, right? You produce considerably less than 1 horsepower. 1 horsepower = 735 watts. And with a 12V battery, that equals a little more than 61 amps. You could do that with an electric furnace fan motor.

But I think that you don't really mean what you said literally. Because in America, when you say "the minimum to get my car moving" it means "75mph in a 55 zone", which is apparently the de facto speed limit. That will cost you at least 192 V, and whatever amps you can spare.

(Disclaimer: This post is entirely silly. The humour impaired should plug their ears and yell 'la la la la la' as loud as they can)


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## Ioku (Sep 27, 2007)

Ive been wondering the same thing the op said about high proformance 
motors. I got a car that weighs about 2700 Lb’s and id like to get proformance like the Tesla car. So what sort of hp and torque moter would I need to get that sort of proformance.


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## Greenflight (Sep 13, 2007)

Well, let's just say there's a reason the Tesla costs 90 plus grand.  They use lithium battery packs and brushless motors- not stuff that's available to the average joe.

You can do it cheap, but you'll end up with a purpose built race car with a 15 mile range- not that it isn't totally cool, just might not be what you're looking for.

Look through the EV photo album at http://www.austinev.org/evalbum/ and see what kind of performance people are getting from different setups. There's a section for race cars too.

gromm, where can I get an electric furnace fan motor? How much do they cost?


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## gromm (Sep 24, 2007)

Ioku said:


> I got a car that weighs about 2700 Lb’s and id like to get proformance like the Tesla car.
> [/SIZE]


Go here for details.

You might want to shave off a few of those 2700 lbs if you want that kind of performance though.

And if you want the same kind of range, you'll have to spend *lots* of money on batteries. Thunder Sky is a well known producer of Lithium Ion batteries for Electric Vehicles.


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