# Need some Tech know how!



## Guest (Dec 3, 2008)

The D&D will be on the smallish side. Go for a larger one if you can. You will be glad you did. 

72 Volts is a bit low but you can do it. I'd say go with 96 volts and better yet go with 120 or 144.

Batteries, Flooded or Glassmatt. Flooded are cheaper but require you to care for them. Glass matt like optima style are excellent choices. For distance you should go with 6 volt or 8 volt batteries. Your car will be a heave monster when done with lead batteries. 

Your requirements really rule out lithium batteries.

You can't just run a torque converter. Torque converters are attached to the auto trans. Use a manual transmission. You will be glad you did. Take the best advice from the gurus. Do what will work. Only do experiments when you know what your doing. 

You should use a manual trans and keep the ability to shift. I'd go clutch set up but others will disagree. 


READ the wiki and other stuff we have here and over at EVDL. A world of info abounds here. 

Check out the garage and do a search on Static Charge. 

Pete : )



Sheldon I said:


> Hi Gentlemen, Ladies.
> 
> I'm contemplating an EV project this summer, but I have some questions, and there seems to be some very knowledgable people on this forum, so here goes.
> 
> ...


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## Guest (Dec 3, 2008)

Oh I forgot! Welcome to the the site and the world of EVs. You have loads of homework to do. We are all glad to help. 

Pete : )

PS. Many of us are still learning too.


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## Sheldon I (Dec 3, 2008)

I think you missunderstood the Torque converter. I'm talking about one thats used in Snow machines or industrial equipment. It consists of 2 parts. One the Clutch/Drive which is controlled by RPM and a moving drive part that changes the belts possition by rotational speed. This belt then turns a drive pully. These together form a comlete transmition with a continuously variable ratio. Below a set RPM the cluch will not engage.

What motor would you suuggest then? 

Thanks for that quick reply! I hadn't even lodged off yet, checking out other questions, and took one last look before leaving and *WOW* and answer already!



gottdi said:


> The D&D will be on the smallish side. Go for a larger one if you can. You will be glad you did.
> 
> 72 Volts is a bit low but you can do it. I'd say go with 96 volts and better yet go with 120 or 144.
> 
> ...


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## madderscience (Jun 28, 2008)

so you mean CVT (continuously variable transmission)

I suspect if you do research on these you will find that they are still less efficient than a standard gearbox.

Note that you can keep a tranny, and still do some things to improve on efficiency over a standard gearbox/clutch setup.

Some ideas:

1) (cheap, easy) Use lighter gear oil than you would normally use in the gearbox, but don't go overboard. Make sure it is synthetic oil as well. I am using castrol straight 30wt in transaxle in my MR2.

2) (moderately expensive, easy) use a lightened or lightweight racing flywheel and pressure plate. Lose the ring gear. You can cut your rotating weight in half easily with an aluminum flywheel and pressure plate, which are available for many performance oriented cars. roughly speaking, knocking 15lbs of rotating weight off a 10" diameter is like taking 50-200lbs of static weight off the car, depending on the gear ratio you are in, when it comes to acceleration.

3) (cheap, but challenging) Modify the transmission to eliminate unnecessary gear ratios. If you know you are never going to exceed 60mph, you can figure what the highest gear you will really need is. Perhaps out of a 5 speed tranny, you only really need 3rd gear to get to 60mph and stay in your RPM range. You can reverse the motor electronically, so you don't need a mechanical reverse gear. With some playing around you may find that by replacing some internal components with spacers and such, you can eliminate unnecessary gear ratios, saving weight and the friction of these parts (which turn even when not in that gear)

4) If its a larger vehicle, use a 2 speed divorced transfer case. Or, find an aftermarket overdrive unit and use it by itself to get 2 speeds. There are a few out there for various, mostly older vehicles.

5) Modify an automatic car transmission to become a single speed gear reduction box, if you are OK with the limitation in top speed.

I've done items 1-3 with my car. Even though there are bicycle and washing machine parts in my transmission, it is working fine. 

Items 4 and 5 among others have been discussion on other threads on this forum in depth. But I do think this is the first time a CVT has been proposed (that I have noticed anyway). good thinking.


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## Guest (Dec 3, 2008)

Well put that way you want the CVT out of a snowmobile. There are actually a few electric snowmobiles and they use the CVT. Putting one in a car may be a bit of a challenge. I still recommend you still stick with the stock transmission and utilize the clutch and pressure plate. I do recommend that you use a lightened flywheel with or without the ring gear and use lighter weight synthetic oil in the transmission. The difference you will notice on a street driven car will be very minimal. Now if you were building a race electric vehicle I would go a completely different route. Keeping the transmission and the gears will allow you to go faster and choose a more ideal gear for the speed you are driving. With one gear you get one ideal speed. With 4 or 5 gears you get a better choice. The extra weight is not as critical as you may think or as critical as others say but you do want to remove as much as you can. Taking out the ICE stuff usually will suffice for weight reduction. Just build it with a bit larger motor and higher voltage. My Ghia has limited space for batteries and using the 6 volt batteries I can maybe squeeze in 96 volts worth. For now I am sticking with 72 volts worth. I can up grade to 8 volt or 12 volt batteries when I want to upgrade my power and speed which will happen at some point. I don't think I could reduce the weight of my Ghia much more either. It is pretty much done. I may get a few more pounds but for me it really is not worth the trouble and I won't see much benefit from that little of weight reduction at this point. 


Use what works. Don't make more work for your self. At least not for your first EV. 

Use the (Keep it Simple Stupid) rule or what is referred to as KiSS.


Pete : )






Sheldon I said:


> I think you missunderstood the Torque converter. I'm talking about one thats used in Snow machines or industrial equipment. It consists of 2 parts. One the Clutch/Drive which is controlled by RPM and a moving drive part that changes the belts possition by rotational speed. This belt then turns a drive pully. These together form a comlete transmition with a continuously variable ratio. Below a set RPM the cluch will not engage.
> 
> What motor would you suuggest then?
> 
> Thanks for that quick reply! I hadn't even lodged off yet, checking out other questions, and took one last look before leaving and *WOW* and answer already!


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## tj4fa (May 25, 2008)

gottdi said:


> ...I still recommend you still stick with the stock transmission and utilize the clutch and pressure plate. I do recommend that you use a lightened flywheel with or without the ring gear...
> Use what works. Don't make more work for your self. At least not for your first EV.
> 
> Use the (Keep it Simple Stupid) rule or what is referred to as KiSS.
> ...


Good advice above.

I just got my Ranger EV done a couple weeks ago (at least enough to drive back and forth to work).

It is a clutchless setup with the original 5 speed transmission and blended synthetic gear oil. 

Since my main gears are 1st to get going and 2nd as pretty much the final drive up to 60 MPH, the 2nd gear synchros get a lot of ahh...ahem..."use" and afraid one day in the not-so-distant future it will resemble a bunch of hamburger in the bottom of the gear sump.

If I do another EV, I think I would like to go with the lightend clutch setup and dreaming a way to do it electrically with an electromagnet setup somehow.

Speaking of dreaming...I'm also wanting it to look like the car in the pictures below: 

http://www.carbodydesign.com/archive/2007/01/31-peugeot-e-motion/

















http://www.carbodydesign.com/archive/2007/01/31-peugeot-e-motion/Peugeot-e-Motion-3.jpg 
http://www.carbodydesign.com/archive/2007/01/31-peugeot-e-motion/Peugeot-e-Motion-2.jpg


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## Sheldon I (Dec 3, 2008)

Ok thanks guys, I think I see that you guys think the CVT idea may not be the best way to go. So I think I'll take your advice. It's just that I felt if they can be used sucessfully in Snow Mobiles, and even in high performance ones, why not in a EV. Being a lazy driver, I like auotmatic tranmissions and a CVT would be as automatic as they come. 

How would you perform a smooth non-grinding shift without a cluck? As I have read some eliminate the cluth. What would be wrong with using a auto transmission?

This opens up many more choices for the donor vechiles, as I can go for a front wheel drive. Do you guys still think that *MO-ES-15A* still too small?

I'm now looking at this Cloud-EV package  Conversion Package 72-120V 6.7" Motor 400 Amp controller

What do you guys think of this package? Too much for a SMALL EV for city use? To get around *50 miles* on a charge are *6 to 8 12v 110 AHr* batts going to cut it? I don't want to be constantly worring about my batteries, and from what I've read about flooded cells they need constant loving care. I've had some experience with *Gel Cells* in other projects (fighting robot, like in Battlebots) and found they will take a fair amount of abuse, both physically and elecrtonicaly. What your opions on AHr size and type.

*P.S.* 
I'm still curious, does anyone really know the max. RPM output of these two motors at say 72V & 92V.
I don't understand why an important spect like this would not be available. Anyone want to take an informed guess?

I would like again, to thank all those who replied to my first question.


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## Guest (Dec 4, 2008)

It is not that we do not think CVT's are bad but it is the fabrication requirements to install one in a small car. That alone would be a major undertaking. For your first EV stick with what works and what has been done that will guarantee success. After that you can go hog wild if you have the time and funds to custom fabricate something that will work. I have no doubt you can make something work but you will need a good shop and an endless supply of patience and money. That is guaranteed. 

The problem with normal automatic transmissions is that you need to spin up the motor to get the transmission fluid moving in order for the torque converter to work. So in other words you need to waste energy keeping the electric motor actually spinning when you come to a stop. Some decided to go this route and is not out of the question. There are some things you can do to some of the older automatic transmissions to make them work fine. 

But for cost and ease of assembly use what works and again make use of your stock transmission. Remember that you really don't need to shift much with the electric but having the ability to shift when you want and need is an excellent thing. 

So why do you need to use an auto transmission on a front wheel drive car? 

Many conversions are 5 speed front wheel drive cars. 

Pete : )

Most series DC motors are rated to 4500 rpm and some a bit more. They are not high rpm motors. They have lots of torque and excellent life. Most DC motors can max out the rpm even with 72 volts. So you must watch your rpms. In high gear you should be able to drive a a decent clip without worry. But in lower gears you will need to be aware of your speed. That is why many install rpm gauges so they don't over rev them. They can die real fast if you over rev them. AC motors are more forgiving but require higher voltage and special controllers. They cost more. 

Have you driven in an EV yet? If not see if you can get a ride in one. You will be hooked. 

Pete : )



Sheldon I said:


> Ok thanks guys, I think I see that you guys think the CVT idea may not be the best way to go. So I think I'll take your advice. It's just that I felt if they can be used sucessfully in Snow Mobiles, and even in high performance ones, why not in a EV. Being a lazy driver, I like auotmatic tranmissions and a CVT would be as automatic as they come.
> 
> How would you perform a smooth non-grinding shift without a cluck? As I have read some eliminate the cluth. What would be wrong with using a auto transmission?
> 
> ...


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## ww321q (Mar 28, 2008)

Just a pic for ya ! .......J.W. 



I would like to see if it would work


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## order99 (Sep 8, 2008)

Sheldon I said:


> How would you perform a smooth non-grinding shift without a cluck? As I have read some eliminate the cluthhttp://www.cloudelectric.com/inc/sdetail/3887.



Most manual trans use a clutch to keep the spinning ICE engine from damaging the trans. Electric Motors don't need to idle-therefore, all you need to do is let up the throttle for a few seconds(the motor stops)and shift the stick.

There's nothing that forbids you from using a clutch, but to some it's extra weight that they can get rid of by a simple delay in shifting.

If I get some scratch together next year I plan to try my hand at EV design-

(keep an eye out for the pretty explosions!!!)

-and if I can build the chassis light enough(Trike design) i'm going to try direct drive. I love that Overdrive Unit idea though, i'll have to check one out!


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## Sheldon I (Dec 3, 2008)

Thanks for all the help guys! I'm still not clear about the motor size for a small EV in the 2000 lb. mark w/o batts.

Will the Cloud EV package I mentioned before be too much or should I go with the *MO-ES-15A *I originally want to.

http://www.cloudelectric.com/inc/sdetail/3887


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## Georgia Tech (Dec 5, 2008)

Sheldon I said:


> Thanks for all the help guys! I'm still not clear about the motor size for a small EV in the 2000 lb. mark w/o batts.
> 
> Will the Cloud EV package I mentioned before be too much or should I go with the *MO-ES-15A *I originally want to.
> 
> http://www.cloudelectric.com/inc/sdetail/3887


If your wanting to go automatic tranny then I would go with a larger motor! A large motor can handle higher amounts of current if they have bigger wires and brushes. Also if they have more turns and more com bars they can take higher voltage! If you want to go automatic I would not look at the D&D motor, even their larger motor does not seem stout enough...maybe an ADC 8 inch. I saw the D&D 31 motor was not too impressed for car application...I think it would be great for a FAST gokart though...


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## Georgia Tech (Dec 5, 2008)

Automatic Transmision is not very effecient, you will loose rang..


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## PhantomPholly (Aug 20, 2008)

ww321q said:


> Just a pic for ya ! .......J.W.
> 
> 
> 
> ...


Kewl pic - is this a racing electric chassis? And, are those dual CVTs?

Seriously, dual CVTs on a front wheel drive (or rear wheel with independent suspension) setup seems like it would be about ideal for an EV. Yes, you lose a touch of range but you would not have to worry about motor overspeed.

Where can someone buy snowmobile type CVTs? I may re-think my plan...


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## Harold in CR (Sep 8, 2008)

Plenty of 'em on ebay.


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## PhantomPholly (Aug 20, 2008)

Harold in CR said:


> Plenty of 'em on ebay.


Any particular makes / models better than any of the others? Any particular features to seek out or avoid?

Also - what do you search on? I searched "CVT" and got sub-woofers and belts, but no actual CVTs appropriate to this usage (expect that each CVT should handle about 50hp for a dual setup).


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## Harold in CR (Sep 8, 2008)

Try Comet clutch. Converters of Motorcycles like the Comet. Have any buddies that live in Snow land ??? Should be gobs of junk snowmobiles. Just try to get a matched set. I plan on an electric motorcycle with a Comet CVT clutch. Already have the Goldwing swingarm, brand new, with wheel and tire. 

No BIG Bikes down here, to speak of, YET.


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## order99 (Sep 8, 2008)

My ignorance of CVTs is as vast as, well...my ignorance of dozens of other subjects.

I doubt i'm the only one either(the former,that is...). So do we have any CVT experts in-Forum who could enlighten us with a quick laundry list of Advantages/disadvantages of CVTs? I'm all ears-er, eyes...


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## Sheldon I (Dec 3, 2008)

I have found a place that has several CVT units that are sized right for an EV .

http://www.hoffcocomet.com/comet/aftermarket-torque-converters.asp#500

The Comet 94C Series Torque Converter, Comet 44C Series "Magnum" Torque Converter or the Comet 103 HPQ Series Torque Converter look promising, although the 103 series has kind of a high cutin speed.


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## PhantomPholly (Aug 20, 2008)

For EVs I think ideally the cutin speed would be 0 (always engaged). That would allow for regenerative braking.

But, realistically I'm probably getting too ambitious for my first project. I just spent a year restoring my plane, and I know how easily "creeping elegance" can greatly extend your effort expended!


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