CarBEN EV5 - Open Source 5 Seat scratch-built Electric Car

I have been designing an electric car for a few years - and this year I started actual construction; using a 3-axis CNC machine called a PhlatPrinter 3 to cut 1" layers of foam. I then glue the layers together so they form a "stair step" rough shape of the design, and now I have been smoothing it.

Lots of pictures here: http://smg.beta.photobucket.com/user/NeilBlanchard/library/CarBEN EV Concept

A couple of the rough shape (with only the front smoothed):


And a couple of the smoother chassis:


Here's me sitting in my high tech bucket seat, in the driver's position in the center front:


The foam will have fiberglass applied both on the outside and inside to form an insulated monocoque chassis. I have a fairly detailed build thread going over at EcoModder.com: http://ecomodder.com/forum/showthre...ized-prototype-construction-5-seat-22529.html

The design and model building thread is here: http://ecomodder.com/forum/showthread.php/carben-model-1-24th-scale-model-3d-computer-11969.html

I'm hoping to have a rolling chassis in about a year from now. Then it will need a drivetrain and hopefully the best battery pack available - I'm aiming for a 50-55kWh or so that will be installed in the floor (see the long rectangular channels in the chassis). The windshield and wipers will be from a Smart ForTwo. The front wheel skirts will be hinged to let the wheels turn sharply, but remain covered at highway speeds.

Please ask any questions you may have!

That is freaking amazing, Neil. When you said you were building an electric car, I thought you meant 'converting' one - not 'BUILDING' an electric car. What is your background? It must be in engineering and design. You really have this well thought out. When you spoke of fiberglass, I remember doing fiberglass repair on surfboards when I was into that back in my military days. Thats a whole other level of fun. Basically, the same thing you are doing - a foam core with a fiberglass shell. Can't wait to see pics of that.

Thanks! I decided at the very beginning that I wanted to have as low aerodynamic drag as possible, so that meant I had to start from scratch. Well, actually it is possible to build a very low drag car starting with another car - have you seen Dave Cloud's Dolphin? It has only two seats, but it can go 200+ miles on its 60 lead acid batteries!

http://ecomodder.com/forum/showthread.php/ultimate-aerodynamic-car-dave-clouds-dolphin-13142.html


But I was already going on the CarBEN EV5 - at the time I wanted to get the Aptera 2e, and when that all fell through, I knew I had to try and built my own. And I need at least 4 seats, and the Mercedes Boxfish blue clay model looked like it would be the perfect starting point.

I got my new flexible sanding tool (from a boat building tool supplier) and after an initial stumble, I figured out how to use it:


It is fine on fully convex surfaces, but I first tried it on the "twisted" shoulder surface and the edges of the sandpaper started digging nasty long gouges in the foam... ;( In the cold the board is not all that flexible and since the paper extended 1/4"+ beyond the board and when the board was bent, the edge sawed into the surface in one stroke. Ouch.

I trimmed off the excess edges of the sandpaper, and when I use it on the convex surfaces along the sides of the hatch opening and on the roof above the driver, it works much better. The 30" length and the 4 1/2" width of the tool let it conform to the long curves, but it still bridges over the low spots. I miss the self-vacuuming of the disk and belt sanders - I now have to wear a dust mask.




Full Slideshow

The smaller tool is obviously homemade - I cut a piece of 1" foam to the width of the 120 grit belt sander paper (it got too much moisture sitting in my basement for years, and pulled apart at the seam). It happens to work quite well for the shoulder and other areas that are too tight for the large sanding tool.

Over the winter, I have continued to occasionally work on warmer days - here is the photo album: http://smg.photobucket.com/user/Nei...cept/DSC_0364_zps7462abc8.jpg.html?sort=3&o=0 The hatch door now fits flush:

I am going to bring my CarBEN EV project to the Framingham (MA) Earth Day Festival, which is happening on April 27th 11:00am-3:00pm at the Framingham Center Common; between Vernon Street, Edgell Road and Route 30; just north of the Framingham Center exit on Route 9.

What I have so far is the entire chassis built from foam and close to being ready for fiberglass. Here's my photo album of the construction process so far: CarBEN EV Concept Photos by NeilBlanchard | Photobucket

Here's the Framingham Earth Day Festival web site:

http://www.framinghamearthday.org/

Here's the Facebook page: https://www.facebook.com/FraminghamEarthDayFestival/posts/393192404113417

Please come if you can, and see the CarBEN EV5 that I have been working on for several years!

If I lived close enough I would go. I would really like to see that car of yours up close.

This is the first time I've seen it at a distance greater than a few feet, since it's been smoothed (and there is more to go!):



Then back home:


Here's a reworked version of the presentation slideshow I had running on my iMac at the Festival: http://neilblanchard.blogspot.com/2013/04/carben-ev5-construction.html

Pictures taken by a friend:

Looks a good time, thanks for sharing the pictures.

Here's a video that I took (I should have done the shake compensation in the camera, so you have to live with the slightly warping compensation in the YouTube fix):

http://www.youtube.com/watch?v=ckUMwbfROyU

Here's a longer, more detailed walkaround video:

http://www.youtube.com/watch?v=A49N2onsN64

I tried the stabilization in the camera, but it still needs the YouTube processing...

It's got it first dirty bird, and there are glue drops and runs, and rough edges... My son will be helping me move it back into the shelter soon, so I can continue smoothing. The left side in particular needs a fair bit of work. They all show up much more readily in the full light of day!

This is how I am using the longboard sanding tool I bought from Jamestown Distributors. It is a tool normally used on boat hulls, and it is nearly perfect for this, too. The swirling motion and figure 8 motion tend to avoid any gouges or divots.

http://www.youtube.com/watch?v=K3d64d3_S-g

I was able to even up the surface so that the several low areas are largely gone.

I wish that my video camera had a wide angle lens - I had to position it quite far away, and I hope things so up clearly enough.

I've been smoothing the bottom and after gluing in some small patches, the diffuser fins are much more even and straight:


(click on thumbnail for larger versions!)

I need to work on the right side and then I will glue up the wheel skirts, and then start fiberglassing the bottom. A windshield (from a Smart ForTwo) will be needed fairly soon as well.

I made samples of fiberglass on the XPS foam I am using to test for strength. Here are some pictures of the fiberglass testing:



This was the worst compression failure, that occurred at ~163.5 pounds pressure. This piece was tested with this damage on the underside for the rest of the testing, and it seemed to have minimal affect on the deflection, if any.



The lighter fabrics started to show some compression damaged at position #3 with ~46.5 pounds of pressure, and most showed a compression dent in position #2 with 77.5 pounds pressure. All samples had a compression dent after testing in position #1 with 116.5 pounds pressure. When possible, the (largest) dent was on the underside on tests after a sample was damaged. This may have exacerbated the deflection in those later tests, but it seemed to be minimal and not change the general pattern of the data.

After testing fiberglass samples for relative strength, I am back to smoothing/shaping with the disk sander and the long board - I am working on the 'A' pillars and the brow of the windshield and the transition to the roof, and on the hatch door.

Neil, not to sound like an idiot, but what exactly are you building? Obviously, it's a car. But is this just going to be a model or an actual working, driveable vehicle? I'm very intrigued either way!

RobbW said:

Neil, not to sound like an idiot, but what exactly are you building? Obviously, it's a car. But is this just going to be a model or an actual working, driveable vehicle? I'm very intrigued either way!

Click to expand...

You must not have read the thread, Robb - It's a real car and he pretty well explains each step of the construction

"The foam will have fiberglass applied both on the outside and inside to form an insulated monocoque chassis. I have a fairly detailed build thread going over at EcoModder.com: http://ecomodder.com/forum/showthread.php/carben-ev5-full-sized-prototype-construction-5-seat-22529.html"

It's coming along nicely, Neil - It's going to be stunning when you're done

Don

Don, no, I had not read the thread here. But I did read through Neil's blog that he linked at the beginning of his post. While it was all very detailed, I could not make out if this was going to be a working vehicle or simply a 1:1 styrofoam concept model from which the real car would be built.

Robb, it's a question I get a lot - it is going to (hopefully) be a working prototype. The composite sandwich construction is not unlike the way a fiberglass boat is made; and was pioneered by Burt Rutan for both airplanes and cars.

Neil, having built/rebuilt lots of boats, I do not envy your ambitious project. Had you considered vacuum bagging (to squeeze out excess resin) and carbon fibre in your skin covering? All the best to you.

Joe,

I have considered vacuum bagging and carbon fiber fabrics, but I am not going to be able to use either. I'm probably going to be using the 40oz E-Glass double plain weave fabric on the underside, and possibly on the inside of the battery bays, and possibly on the 'A' pillars and on the other pillars, and on the rear door openings. I like the 8.9oz 8-loom fabrics for most other things, and use the lightest fabrics only in a few non-critical places.

I need to do a crowd funding campaign (Kickstarter or similar) to get this project proceeding much more quickly. The next purchase I need to make is to buy the Smart ForTwo windshield and I need to buy at least the 40oz fabric, so I can get back inside CarBEN to work on the driver's seat, etc.

The CarBEN EV5 BEV



The background on this is I was able to be at the X-Prize Knockout Round as a guest member of the Edison2 team, and while I was there I meet and talked to many of the people, and to see what they had built, and all the effort and passion that went into it. Jason Fagone has written a enthralling and detailed book about the X-Prize, called 'Ingenious' and he and Kevin Smith of Illuminati Motor Works are touring with the IMW 'Seven' electric car.

Seeing the IMW Seven and talking to Kevin Smith and to some of the folks at the MIT Electric Vehicle Team has got me thinking more about the main electric drivetrain for CarBEN EV5 - which is a 5 seat electric car that I am currently building. I've been concentrating on the design and how to construct it, so this is a first take on the drivetrain components:

I like the looks of the BRUSA SSM1-6.17.12 along with the Getrag GX629 6.4:1 EV Transaxle assembly. That puts the ~ 5,500 RPM which is the peak efficiency of the motor right about 55-60 mph (depending on the tire diameter you use).

No rare earths used and lower cost (though certainly not inexpensive), and a compact package (roughly 11" x 20"?) with no 90º turns - we may have a winah!

The batteries used in Seven are the Thundersky (now CALB) 100Ah cells.

I can fit 106 of these in CarBEN EV5 (Seven has 99) and Kevin Smith swears by them and their ruggedness. That would be ~ 35.3 kWh and cost roughly $16,000. They use no BMS and do a "bottom balance" and have stopped seeing stress that occasionally caused the cells to swell.

I had used the EiG 20Ah pouch/prismatic cells in my planning and I could probably fit about 50 kWh into the compartments in the floor. FVT has an innovative BMS system that shunts the excess from one cell to another cell that is still charging; rather than to ground - as I understand it. This should be more efficient than ordinary BMS.

I looked briefly at the A123 cells, and these are wider than would easily fit in the battery compartment I have in CarBEN. And they are very hard to find, if not impossible.

A choice for charger is still vague. Seven has a Manzanita, and it works well. They disconnect it on the inside, so that regen doesn't blow it out.

One of the MIT EVT people has put me in touch with their Porsche guy, and I have asked about getting the rear suspension from a 914. He is a busy person (post grad?) and I will wait and see if he can help me. Up until now, I've been thinking of using the front suspension of a Saab 900. But I'm also going to look at the Neon front suspension that Seven uses (in the front and back), though I don't think it could fit in the back of CarBEN, and I don't need the Prelude rear wheel steering; as the wheelbase of CarBEN is significantly shorter.

It looks like all this hardware will cost $35-40K, which is actually about what I was expecting.

The Illuminati Seven sets a high standard for efficiency: it uses just 129Wh/mile at ~60mph, and it has a 220+ mile range at 60-70mph. The EPA rating (tested by Chrysler at their proving grounds in Chelsea MI) for 7 is 207MPGe.

Which is something to strive for.

Would a Coda car be useful for batteries and parts? I called and was told a brand new car was under $16,000 or so shipped. http://codacars.com/.

Sadly, CarBEN has suffered damage when its temporary shelter collapsed from snow overload, videos here and on a preceding post on that EcoModder thread:
http://ecomodder.com/forum/showthre...-construction-5-seat-22529-55.html#post403415