# EV from Scratch



## ga2500ev (Apr 20, 2008)

sergiu tofanel said:


> Am I nuts for thinking about reinventing the wheel?


Yes and no. Yes because the average DIY EVer is not prepared to put a car together from scratch. Also there are significant issues in terms of getting kit cars built from scratch registered to run on the road.

The cutthough on this is putting a custom body on a VW Bug chassis. The chassis is little more than a rolling pan that a fiberglass body can be bolted onto. And since the doner is a car with a VIN, there are no registration issues.

Few will want to start the mechanicals from scratch. Think about the body.

ga2500ev


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## Duncan (Dec 8, 2008)

Hi Sergui

Do you have any idea how much engineering time is required to design a new car?

Think of 500 man years and go up from there - and no that's not because of government regulations 

It is possible to design and build a car from scratch but you will have to adapt a whole lot of existing parts and lose a lot of sophistication

If you have ever built a kit car you would realize that when the damn thing is sitting there with all of the drive train and suspension in place - you still have 90% of the work to do
Its all of the little things that take the time

Aerodynamics is a bit like that as well - you glibly talk about a CD of 0.2
That is easy to get with a simple shape moving through the air

Bloody difficult to get in the real world with all of the inter-reactions with the ground not to mention all of the edges of panels, doors, windows

GM probably spent several hundred man years of engineer time (not to mention testing) to get the EV1 down to 0.19


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## Snakub (Sep 8, 2008)

I think you should go ahead and try it but if you are going to build a whole car why go with a frame or pan at all go monocoque. With that all you need is a suspension on both ends and forget about the front have the engine in the back so the windshield can be as close to the front as possible to maximize the airfoil shape. Also, why worry about the interior so much? Just have it be as minimal as possible. Were both in the same frame of mind right now I'm doing drawing after drawing and looking into getting my foam and clay skills up to par!


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## sergiu tofanel (Jan 13, 2014)

Snakub said:


> I think you should go ahead and try it but if you are going to build a whole car why go with a frame or pan at all go monocoque. With that all you need is a suspension on both ends and forget about the front have the engine in the back so the windshield can be as close to the front as possible to maximize the airfoil shape. Also, why worry about the interior so much? Just have it be as minimal as possible. Were both in the same frame of mind right now I'm doing drawing after drawing and looking into getting my foam and clay skills up to par!


I was thinking along the same lines. What I have in mind is a vehicle roughly the size of a Mini Cooper, but with much better aerodynamics. I do have a CNC machine big enough that will cut the plugs for the body panels in order to make the molds. The chassis could be tubular space frame, or some kind of monocoque/pan combination. My only dilemma right now is how to get a DOT certified windshield without breaking the bank.


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## Snakub (Sep 8, 2008)

What range are you shooting for? What batteries are you thinking about? Motor/Controller/Performance etc?


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## sergiu tofanel (Jan 13, 2014)

I recently acquired a Bombardier NEV. I know, it's nothing more than a glorified golf cart, but I am thinking about using its drivetrain for now. It has a 5HP-25HP DC motor with a Curtiss 300A controller, running at 72V. If my calculations are correct, I'll need approx 10HP (7KW) to move a well designed car at 60mph. The Bombardier will not quite do, but it's a start. For batteries I am thinking Nissan Leaf packs. There is a company selling 10KWh usable packs for less than $3000. This should give a range of 60-100 miles per charge.


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## PStechPaul (May 1, 2012)

It might be a good "cottage industry" to select suitable existing vehicle frames and strip them down ready for adding batteries, motor, and controller. Then they could supply a body chosen from a selection, or possibly manufactured to specification or drawing. The components could be made using a 3-D printer and/or CNC machine. Of course, much of the appeal of DIY is the challenge and pride of a full retrofit, but that may be beyond the ability of some who would rather just design and install the electrical drive system.


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## sergiu tofanel (Jan 13, 2014)

PStechPaul said:


> It might be a good "cottage industry" to select suitable existing vehicle frames and strip them down ready for adding batteries, motor, and controller. Then they could supply a body chosen from a selection, or possibly manufactured to specification or drawing. The components could be made using a 3-D printer and/or CNC machine. Of course, much of the appeal of DIY is the challenge and pride of a full retrofit, but that may be beyond the ability of some who would rather just design and install the electrical drive system.


That is always an option for most DYIers. MY problem is that ICE platforms were not designed with mechanical and aerodynamic efficiency in mind. The design priorities for automobiles are as follows: marketing, regulations, and dead last being efficiency/cost of ownership. If it were not for the price of gas and CAFE standards, all cars today would have 300hp engines getting 15mpg. Right now the equilibrium point seems to be a platform that gets 30-40mpg. This is nowhere close to an EV platform, which when converted to ICE, should get at least 100mpg.

That being said, all DIYers must approach their projects with their particular skill set in mind. Mine happens to be mechanical design and fabrication. I can fake electrical engineering, but that's not my strong suit. I am still convinced that in order to make an leap forward in EV performance we must ditch the ICE platform and start from scratch. Whether that can be done within the DIY community, that's another matter.


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## jhuebner (Apr 30, 2010)

Ever heard of this: http://www.theoscarproject.org/

oscar stands for Open Source Car.


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## sunworksco (Sep 8, 2008)

You may consider using Alulight all metal aluminum foam panels for your monocoque chassis. You can source out 9mm thick panels in Europe or China.
It can be tig welded or expoxied together.
Reverse trikes are a good platform and save weight by using motorcycle parts and can be licensed as a motorcycle. Ducati and BMW F800 single sided swing arms can be used to a great advantage.


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## sergiu tofanel (Jan 13, 2014)

The aluminum seems like a great idea, but for availability. I searched everywhere and found no reasonable US suppliers. Furthermore, the little I found is priced like aerospace products: triple the cost. 

I always liked the reverse trike idea. Much simpler than a car, but in most of the US one will be forced to wear a helmet while driving. I don't know what are the loopholes to get around this. I live in Texas, and registering a component car here is very easy. Besides having to prove the provenance of the parts, the car must pass a simple technical safety inspection and voila! you get a piece paper to take to the DMV and get a car title.


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## sunworksco (Sep 8, 2008)

Alulight

Joe Casillo
Isotech, Inc.
777 Schwab Road, Suite T 
Hatfield, PA 19440 
[email protected]
www.isotechinc.com
Toll Free: (800) 314-3332 
Phone: (267) 663-5555
Fax: (215) 631-9148
Cell: (215) 817-3889


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## ga2500ev (Apr 20, 2008)

sergiu tofanel said:


> That is always an option for most DYIers. MY problem is that ICE platforms were not designed with mechanical and aerodynamic efficiency in mind. The design priorities for automobiles are as follows: marketing, regulations, and dead last being efficiency/cost of ownership. If it were not for the price of gas and CAFE standards, all cars today would have 300hp engines getting 15mpg. Right now the equilibrium point seems to be a platform that gets 30-40mpg. This is nowhere close to an EV platform, which when converted to ICE, should get at least 100mpg.
> 
> That being said, all DIYers must approach their projects with their particular skill set in mind. Mine happens to be mechanical design and fabrication. I can fake electrical engineering, but that's not my strong suit. I am still convinced that in order to make an leap forward in EV performance we must ditch the ICE platform and start from scratch. Whether that can be done within the DIY community, that's another matter.


I guess my question is exactly to what end are you seeking in terms of performance goals? On the one hand optimizing to the bleeding edge has utility in furthering basic research. But on the other as you pointed out above that marketing is not only the primary vehicle for car manufacturers but is also the primary motivator for all but the most discriminating user.

The short of it is that the changes necessary to optimize the efficiency of a vehicle are exactly polar opposite to entice anyone other than an enthusiast to consider it.

In all honesty the biggest leap forward any of us could make is to put together an EV that is indistinguishable from a Toyota Corolla or a Honda Accord other than having to recharge it every evening.

Now that does require some optimization I admit. However, no matter how efficient your redesign may be, if it strays too far from what the common public understands, it'll be dead in the water.

My suggestion of performance goals are actually pretty simple. Take a current Nissan Leaf type design. Make it go 250 miles per charge. Have it so that it can recharge in 10 minutes or less. Keep the cost within 30 percent of the current cost of a Leaf.

That's it. That is pretty close to the perfect EV platform for today's world. And it doesn't exist. 

I'm glad that several of you are pushing the envelope. However, if the ultimate goal is wide scale adoption of EV technology, you can see that the target above would get us infinitely closer to that goal.

ga2500ev


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## sergiu tofanel (Jan 13, 2014)

ga2500ev said:


> I guess my question is exactly to what end are you seeking in terms of performance goals? On the one hand optimizing to the bleeding edge has utility in furthering basic research. But on the other as you pointed out above that marketing is not only the primary vehicle for car manufacturers but is also the primary motivator for all but the most discriminating user.
> 
> The short of it is that the changes necessary to optimize the efficiency of a vehicle are exactly polar opposite to entice anyone other than an enthusiast to consider it.
> 
> ...


There is a reason we are having this discussion in diyelectriccar.com and not in soccermomcar.com. You hit the nail on the head in your assessment that in order to make the electric car popular, the car companies must make it indistinguishable from an ICE Honda Civic. That is true for the general public, but not for the EV enthusiast. What I am proposing is not redesigning the EV for the masses (that's GM's and Tesla's job), but redesigning the EV for the EV car enthusiast. This means that one can make design compromises in favor of efficiency at the expense of styling and some practicality. I have no interest in building an electric car for the soccer mom. That being said, let me walk you a bit through my thought process.

I was wasting time on the internet a while back when I stumbled across several diy hypermileage vehicles. One of them is the so called Aero Honda:

http://www.aerocivic.com/

One link led to another, and I stumbled upon this:

http://ecomodder.com/forum/showthre...boat-tail-extension-cardboard-tuft-25223.html

Both vehicles claim a Cd of less than 0.2, with ICE fuel consumption in the neighborhood of 90+ mpg at 60mph. So that got me thinking: why not start fresh and redesign the EV platform with these aerodynamic features in mind? As DIYers we don't have the resources and the know how to improve battery technology. That's better left to the academics and the companies with deep pockets. However, we have the resources to build an efficient platform that takes advantage of the battery technologies available today and those coming up ahead. 

I have been working on a body design for the past month or so, and I'll post CAD screen dumps once I figure out how to upload images into a post (apparently the current setup only allows me to post links). But here are the basic specs:

Length: 132" (3.4m)
Width: 64" (1.6m)
Height: 46" (1.2m)
Ground Clearance: 6" (0.15m)

Add full wheel fairings to both front and rear wheels, add a kammback to the rear (not as pronounced as in the examples above) and one could manage a Cd of 0.2 or better. It will not look like any other car on the road, but I think it will look good nonetheless. A car like this that weighs in the 1000 lbs neighborhood only needs about 10HP to move at 60mph.


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## sergiu tofanel (Jan 13, 2014)

Here you go:


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## sunworksco (Sep 8, 2008)

Very nice design.
Have you considered a reverse trike design?


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## sergiu tofanel (Jan 13, 2014)

I suppose that the body could be tweaked into a reverse trike version. My only concern is the inconvenience of licensing it as a motorcycle and the helmet laws that accompany such designation.


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## Duncan (Dec 8, 2008)

Reverse trikes offer no real advantages in a side by side seating car - they actually waste interior space compared to a 4 wheeler

Your design looks OK but you have already given away some of your 0.2 CD goal by the stylistic bulges

The devil is in the details to achieve a 0.2 CD all of your joints, door panels, air vents, undertray, wheel arches 
Have to be designed properly - and wind tunnel tested 

And then there is the interior

If you are willing to put up with a racing type interior that is not a problem
If you want something comparable to a modern car then there are man years of design to get it right

Don't get me wrong - you can design a car from scratch
BUT you have to decide on your acceptable compromises 

Cost/Performance/Interior/Comfort/Aerodynamics/Weight/Safety/Endurance/Luxury

You can design a Lotus 7 type of minimalistic car 

What you can't do is match a modern car - unless you are willing to spend the megabucks

http://www.diyelectriccar.com/forum...-dubious-device-44370p2.html?highlight=duncan

My own compromise was,
Cheap, performance, fun


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## sunworksco (Sep 8, 2008)

Very true.


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## sergiu tofanel (Jan 13, 2014)

This is by no means the final body shape. I plan to at least run the body through a CFD program like OpenFoam and tweak it from there. As far as the interior is concerned, I envision a fiberglass dashboard and center console, some kind of inner door shell. My goal is to develop a rolling platform that a DIY builder can finish up with his/her own drivetrain.

I realize that such a project does not benefit from the resources that car companies have. Look at this endeavor as nothing more than laying a foundation: an efficient, robust platform that CAN be an alternative to the ordinary.


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## ga2500ev (Apr 20, 2008)

sergiu tofanel said:


> There is a reason we are having this discussion in diyelectriccar.com and not in soccermomcar.com. You hit the nail on the head in your assessment that in order to make the electric car popular, the car companies must make it indistinguishable from an ICE Honda Civic. That is true for the general public, but not for the EV enthusiast. What I am proposing is not redesigning the EV for the masses (that's GM's and Tesla's job), but redesigning the EV for the EV car enthusiast. This means that one can make design compromises in favor of efficiency at the expense of styling and some practicality. I have no interest in building an electric car for the soccer mom. That being said, let me walk you a bit through my thought process.


That is helpful. I wanted to know who the target audience is supposed to be.



> I was wasting time on the internet a while back when I stumbled across several diy hypermileage vehicles. One of them is the so called Aero Honda:
> 
> http://www.aerocivic.com/
> 
> ...


No argument with the premise. I think the issue with virtually all DIY EV people is that it's tough enough trying to do a conversion on an existing platform. Trying to build a platform from scratch is simply overwhelming.



> I have been working on a body design for the past month or so, and I'll post CAD screen dumps once I figure out how to upload images into a post (apparently the current setup only allows me to post links). But here are the basic specs:
> 
> Length: 132" (3.4m)
> Width: 64" (1.6m)
> ...


How exactly does it vary from the Honda Insight or the GM EV1?

ga2500ev


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## sergiu tofanel (Jan 13, 2014)

ga2500ev said:


> How exactly does it vary from the Honda Insight or the GM EV1?
> 
> ga2500ev



For the sake of comparison, let's consider sizes. 

EV1: frontal area = 21ft^2
length = 14ft
thickness = 32% (sqrt(frontal area) / length)

Insight: frontal area = 20ft^2
length = 12.9ft
thickness = 35%

DIYEV = frontal area = 17ft^2 (approx)
length = 11ft
thickness = 37%

At first glance is looks like DIYEV comes at the losing end of the drag coefficient, being a much stouter body. However, even with GM's EV1 there is room for improvement. During the development phase and the subsequent land speed record run, GM's Impact actually had a Cd of 0.167 with the addition of a boat tail and wheel fairings. 

So given the thickness ratio of 37%, let's assume an Insight-like Cd of let's say, 0.30. A perfectly smooth underbody (which the Insight does not have) is worth as much as 0.09. Let's say the Insight is not half bad, so the improvement is worth 0.05 drop in Cd. Wheel fairings (if designed well) are worth as much as 0.04 drop in Cd. We have 2 extra wheels covered, so that's worth 0.02. So far, given a smooth underbody and 4 wheel fairings, let's expect a 0.07 drop in Cd from a baseline of 0.3, which gives us Cd = 0.23. The rest of 0.03 drop in Cd comes as follows:

- much smoother transition between hood and windshield. The angle of the windshield and the hood are the same. 

- a much smaller blunt area in the rear by creating a diffuser behind the rear wheels. I am still combing through academic papers on relevant research on the subject. 

- passive flow control to reduce rear wake. This idea may turn out to be a crapshoot, but I am considering installing either NACA ducts or outright air intakes above the rear wheels. The air is to be routed to the rear corners of the car where it will interfere with trailing vortex formation. This is the automotive equivalent of adding wingtips to an airplane wing to decrease induced drag.


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## ga2500ev (Apr 20, 2008)

One question: exactly how do wheel fairings work on wheels that have to turn? Do they jut out from the body? Or do they turn with the wheels somehow?

ga2500ev


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## sergiu tofanel (Jan 13, 2014)

I would place the wheels sufficiently inboard so the fairings do not have to open at high speeds (for obvious reasons). At low speeds it's a different story. The fairings will definitely have to open. This is the part of the design that is to be determined. I am strongly favoring a hinge + electrical actuator mechanism, because it seems to be simple from a mechanical point of view. But nothing is set in stone.


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## Dustin_mud (May 22, 2012)

My Ev project is a full tube chassis build from DOM, I'm building a 4x4 and I found my jeep would be just way to fat so I ditched all of it other then the vin plate and title. Being in Texas and the jeep title so old I just get classic tags and don't even have to worrie about any inspection.

What part of Texas are you in? I also have had many ideas on building cars from scratch but more style and preformance.


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## sergiu tofanel (Jan 13, 2014)

Dustin_mud said:


> My Ev project is a full tube chassis build from DOM, I'm building a 4x4 and I found my jeep would be just way to fat so I ditched all of it other then the vin plate and title. Being in Texas and the jeep title so old I just get classic tags and don't even have to worrie about any inspection.
> 
> What part of Texas are you in? I also have had many ideas on building cars from scratch but more style and preformance.


I have no concerns about registering a scratch built vehicle in Texas. As long as it passes the basic safety inspection (brakes, lights, horn, etc), all is good. Since the car is an EV, there are no emissions to worry about. 

BTW, I live in Waco.


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## sergiu tofanel (Jan 13, 2014)

Here is a first crack at that 0.20 drag coefficient. This is an OpenFoam screen shot showing the trailing wake at 40mph. The body suffers from high lift and flow separation near the front wheel wells. Still, Cd = 0.22. 

I'll post more as I make modifications.


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