CarBEN EV5 Full Sized Prototype Construction - 5 Seat Electric Car From Scratch

[sheepdog 44]

Hey Neil, would you be willing to press your CNC machine into service for community members? Maybe make some extra money to defray the cost of the CNC machine?

I know i would love a boat tail, and others a streamliner fairing for motorcycles/bicycles. Printer cut sections of foam would seem to be the most economical diy solution for these items. It would "streamline" the build process for many. And most of us find buying finished fiberglass items from molds cost prohibitive.

[NeilBlanchard]

The location in MA is the same one in Lancaster that I drove to two weeks ago. They are either not in business any more, or they just do auto wholesale. I also called another large used parts yard then, and they have nothing. The Smart ForTwo is not a common used parts car.

I'm going the Boston Mercedes dealer tomorrow.

[HydroJim]

You're much better off with all new parts for an all new car. Having a used windshield, no matter how clean, would just look out of place.

[NeilBlanchard]

I went to the Smart Center Boston - which is actually in Somerville - and I ordered the windshield, full wiper assemblies, and the vent bezel that is at the base of the windshield and that the wipers mount to. they will be here this week, so I;ll pick them up next Saturday. It all cost $880.12, which is not bad, really.

I also checked on the (nearly) smooth Smart wheel covers, and they cost $40 each. Not cheap, but they are an option.

Oh, and my wife test drove the Smart Electric Drive, and she loves it. They come with alloy wheels, but I'm sure you can switch back to the smooth-ish wheel covers on steel wheels.

[NeilBlanchard]

Today I picked up the windshield, and the full wiper system, and the vent bezel!



Here they are just sitting in the approximate position:




The windshield is a bit narrower at the top than I had anticipated, but that is a good thing, I think. Remember, the chassis was based on a 3D model of the Smart ForTwo that I got off the Internet, and while it was proportionally accurate and very detailed - it was scaled quite large, so I had to try and base the adjustment on the wheelbase of the car.

I am relieved that it looks like it will work. Very relieved.

[HydroJim]

Big Milestone!

How much progress do you think you'll be making during the winter?

[freebeard]

The windshield is a bit narrower at the top than I had anticipated... Remember, the chassis was based on a 3D model of the Smart ForTwo that I got off the Internet

Considering the provenance, and that it was sliced and hand assembled, that's pretty good. The windshield area wasn't sanded. How does the contour of the foam match the glass, in general? You can see the inner surface of the glass against the foam. 1/10th inch? More/less? You could wet (ink?) the inside of the glass and press it against the foam and get a data point on how close the raw contours were.

Are the A-pillars solid foam so you can just adjust the contour with your sander?

Last question:What steps did you take to insure there wasn't a longitudinal twist as the slices were assembled (I understand they were stacked on wooden dowels)?

Anyway, congrats on the milestone.
______

Edit: There's an interesting article on Wired about the tension between hand-shaped and CNC surfboards.

http://www.wired.com/playbook/2013/0...ilt-world/all/

Your project is in an interesting middle ground.

[rmay635703]

There have been several $4995 fix er up salvage title Smart cars in our local auto paper. Buy the whole car and part ?

They were both runs and drives but had front end damage.

[NeilBlanchard]

The Smart is a fairly rare car, and the one used windshield *listing* was for $200. The new one was $300, so I'm fine with that. The wiper assembly was ~$415, and the bezel piece was ~$106; so with the sales tax the total was ~$880.

I'll get a good look at it soon, I hope, but the overall contour looked pretty close. The 'A' pillars have some volume to them, and sloping the upper part in more will be a good thing; making it more rounded.

I'm working full time at least through the end of November (which is how I had the money to buy this!) and I'll also be getting lot of fiberglass fabric soon, too. But as I'm earning money, I won't have much more than a few hours a week to work on the chassis. I want to glue the nose on, flip it over and get the fiberglass on the bottom, before cutting the windshield hole. I may fit the bezel on, and see what it will take to fit in the wiper linkage and motor; and then glue on the nose. And it takes warmth to do gluing.

Yes, I had 1/2" holes through the layers, and I had 4 wooden dowels to align them. The main problem I had was "pinching" on the sides next to the hatch door. I already added connector struts across the hatch door every foot or so, to keep them at the proper position; so the next one I build will be better.

[NeilBlanchard]

Okay, 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. I like the looks of the BRUSA SSM1-6.17.12 ( BRUSA SSM1-6.17.12 | Metric Mind Corporation ) along with the Getrag GX629 6.4:1 EV Transaxle assembly ( GX629 6.4:1 EV Transaxle assembly | Metric Mind Corporation ). That puts the ~5500RPM which is the peak efficiency of the motor right about 55-60MPH (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: CA100FI 100Ah, 3.2V, 0.3-2C CALB EV LiFePO4 Lithium Battery

I can fit 106 of these (Seven has 99) and Kevin Smith swears by them and their ruggedness. That would be ~35.3kWh 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: EIG Cells and I could probably fit about 50kWh 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.

I looked briefly at the A123 cells, and these are wider than would easily fit. 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. He is a busy person (postgrad?) and I will wait and see if he can help me. 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.