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  #1  
Old 11-18-2007, 01:14 AM
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Default Building from the ground up.....

I am still a newbie here, so please be gentile, I hope this is the correct forum for this discussion.

I am planning to build an electric car from the ground up, the idea is to combine as much of the best technology as possible and I'm hoping to get some imput, ideas, or just opinions. The idea is to sell these cars, if the prototype is a success, and there is interest in it.

The solectria sunrise seems to be the closest example of what I have in mind, and if it ever becomes available as a glider, I would definately consider using it as the platform.

Structure

I want this car to be as light as possible, so composite is the preffered material. For cost reasons, carbon fiber will not likely be used for the entire structure, but instead will be used in structurally stressed areas (its my understanding that the sunrise was built with this in mind), although if cost permits, I will use more carbon and kevlar. I also will try as much as possible to use foam core double wall construction. The idea is to use high impact foam in areas like doors, pillars, fenders, and bumpers to act as impact protection, foam has a unique ability to absorb energy in a controlled and consistent manner, but it will also keep wind noise down (engine noise will not be a problem ). I am also considering adapting a mustang fastback replica f/g body to custom chasis, I thought of using a kitcar body, but I am after a four seat car with a hard top. I want opinions here, would you rather have, classic muscle car, or arodynamic cruiser?

Drive system

My first choice would be a wheel motor setup, and there are a few available out there. Some use an integrated planetary, while others can perform well with zero gearing. Since I am after as long a range as possible, efficiency is the first priority, so I figure a 3ph AC system is best. DC brushless is also good, but I am conserned about having expencive and powerfull magnets in the wheels which are likely to get knocked around once in a while, and AC motors tend to be less costly to build. Wheel motors would easily make the car Awd with effective regen braking as well.

Second choice would be a central motor either at the front or rear of the car, or even both ends, at the expence of weight and potential battery storage, what would you folks figure? front, rear, or all wheel drive (with awd sacrificing some range)? I am in canada, so cold weather operation will be a factor. I'm leaning more towards an AC motor here too, while a DC brished motor will be much cheaper to buy, AC has a wider RPM range, higher efficiency, and is easier to operate with Regenerative Braking.

The transmission would probably be a fixed ratio in the case of a central motor, since this car will not be built for much faster than 80 MPH. However I want this car to have power to spare for those who want to keep up with traffic. A central motor will also mean moving parts like CV shafts, so this is not something I like, but for now I won't rule anything out.

Suspension

Since this car will not be built to compete with the tesla roaster, I fugure 4 wheel McPherson suspension is the best choice, since it give satisfactory handling, while at the same time spares as much interior space as possible. Front and rear components, as well as side to side components will be made interchangable as much as possible. I am toying with the idea of using an air ride suspension, since there isn't much weight penalty, and it would offer a ride quality to match the quietness of the car, but it also gives a certain tunability as well. Since this is pure electric car, 50/50 front to rear weight distribution seems like a good idea, and I will aim for that.

Steering

Not much here, but I am wondering if I should bother with powersteering, since the car will hopefully weigh 2000lbs or less, and range is the priority here.

Batteries

Hmmm....Well, there are some choices these days. Lead acid is not my first one, and frankly, I would not like using them.

Nickel cadmium are still kicking around, but overall are just not good enough to justify the cost, weight, and relatively short life.

Nickel Hydrides are better, but they could be difficult to get, and again are rather heavy for their energy strorage. BUT, they do have fairly a good track record powering the OEM Rav4s, so I would consider using them (assuming a supplier will actually sell them).

Lithium Ion seems to be the one invention of our time that could kill off crude oil AND the Hydrogen fuel cell, and there are many variants to choose from, although, not all of them are actually available to some one like me.

The first gen lithuim batteries are a safety consern for me, and also have a short calender life, so I will preffer to avoid tesla motor's solution.

Lithium Iron Phosphate seem to hold promise for safety, price, and cycle life, but can ThunderSky be trusted? If any of you have had used these batteries, please share your experience, because as it is right now, they seem to be the best bang for buck in terms of performance and cost.

Electrovaya is a canadian company that has made its living on notebook computers and batteries for them, but has also pioneered a "super polymer" battery, which they deployed in a converted vatara. They claim to have broken the 300wh/Kg barrier, and are still making improvements. Unfortunately, I can't get a reply to any of my Email inquiries, and thus far cannot make a fair assessment of how siutable this battery may be, but if you believe their claims, it can deliver everything from hard accelleration, to cold weather operation, to the holy grail of the electric car, LONG RANGE!!

Lithium sulphur is one of my personal favorites, because they have achieved an impressive energy dencity as well, and unlike electrovaya, they do answer Email inquiries, even if their technology is 5 years away, and has been for a while now, hmm......we shall have to see. They claim to be at the 350Wh/Kg mark now, and are within reach of 600 in the "near furure", but 300 cycles are as much as they are willing to claim.

The nannosafe battery is also a good performer, how can you argue with 15 000 100% DOD cycles? (with only a 15% capacity loss) But as with other pioneers, they don't seem to be too keen on dealing with small fry like me, but if I can ever get a price, and (heres some REAL wishfull thinking) if its reasonable, then I would definately consider using them. Being able to offer an unlimited distance 15 year waranty has a certain ring to it. After all, electric cars are more reliable than ICE powered cars.

Final thoughts

Well, first of all, sorry for the long post.

The overall idea here is not to build a car as cheap as possible, but to make something that can fill the gap between the testa, and the low speed NEVs that like to tie up traffic. But more importantly, to remove the last remaining stigma that electric cars have, limited range.

Time will tell if I can ever do anything about this, but for now I'd like to know what you all think.
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  #2  
Old 11-20-2007, 11:26 AM
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Default Re: Building from the ground up.....

Hmm....23 views and zero replies, did I go too far???

The idea here is to start a discussion on what we hope for in an electric car, surely some one has something to add here.
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Old 11-20-2007, 01:04 PM
pandaran pandaran is offline
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Default Re: Building from the ground up.....

I'm still in the research phase, so I don't have much to add to all of this yet, but it's nice to see some opinions and comparisons on different battery types.
My chief concern at the moment is the money factor. Gas prices are going up and up, and it makes me angry that I am being forced to pay for them when there are viable alternatives that should cost less.
However, it's really exciting to see someone doing research into improved range! At some point in the future I would definitely like to go entirely EV (unless an even better alternative pops up in the meantime). I'm very interested if you could post information on the price ranges for the different battery chemistries whenever these companies get around to responding to you! Maybe you could even put it in the wiki.
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Old 11-20-2007, 01:36 PM
Mr. Sharkey Mr. Sharkey is offline
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Default Re: Building from the ground up.....

Quote:
Originally Posted by david85 View Post
Hmm....23 views and zero replies, did I go too far???
Um, well, we're kind of overwhelmed thinking about building from the ground up. Maybe the forum needs a new section: DIY Electric Car Factory!
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  #5  
Old 11-20-2007, 03:23 PM
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david85 david85 is offline
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Default Re: Building from the ground up.....

Thats what I was afraid of. What I put fourth is my interpratation of the ideal electric car, and some ideas to make it possible. But that doesn't mean we can't discuss more basic aspects of the idea by themselves.

The idea here is to further the knowlage of the technology, and in that respect, I think everyone here can contribute, even if its just to comment on the idea.

pandaran,

I have been in the reasearch phase off and on for the last 8 years, and I still have a lot to figure out, for now this is just a side project of mine, but I am begining to see the potential for something real here (technology as well as market acceptance). Cost is big obstacle for me too, but for now my car is just an idea.

If I can help with your project (or anyone else who is whatching) by sharing my reasearch, I will post more detailed info here on some of the technology I have mentioned as time permits.

Should I start with batteries first? Range seems to be the most consistent problem with electric cars.




(I will also bring ICE powered range extenders into the topic later on if thats OK with everyone)
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Old 11-20-2007, 03:26 PM
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Default Re: Building from the ground up.....

Check out www.rqriley.com, if you haven't already. They sell plans for a bunch of cool DIY cars and stuff. Most of them have foam core/fg/cf bodies (I definitely think that's the way to go for a custom car). You might get a few construction ideas looking at them. And BTW, go for aerodynamic cruiser. Muscle cars are cool as classics, but that's a little too retro for my taste!

I'm thinking power steering is kinda pointless for a car in this size range... Maybe some kind of variable ratio manual steering?

And yeah, definitely keep us posted on what you find out as far as battery pricing. We're all waiting with bated breath.

Good luck. Not a lot of folks have built custom electrics. It'll be interesting to see what you come up with!
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Old 11-20-2007, 04:18 PM
pandaran pandaran is offline
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Default Re: Building from the ground up.....

Quote:
Originally Posted by david85 View Post
(I will also bring ICE powered range extenders into the topic later on if thats OK with everyone)
If you're talking about PHEVs, I'm very interested in that! For my first conversion I'm going to keep it as cheap and simple as I possibly can, since I have no mechanical background and very little electric (I know! What am I getting into?!), but the idea of an electric car with possibly diesel or Biodiesel as a backup is intriguing. I've seen a little bit about it, but haven't had the time to read the articles or blogs in depth.
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Old 11-20-2007, 05:20 PM
EricN EricN is offline
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Default Re: Building from the ground up.....

I am currently in the middle of building a replica of a GT40 from scratch. I spent years designing the frame in AutoCad, I have spent $$$$ on engine and transmission parts and put many hours into building the molds for the body. I will tell you the one thing you are going to run into trouble with. By the time you get anywhere, something new is going to come out and you are going to change your original design and go with it. This will happen over and over again. Unless you find a semi-built kit car to work with or something that is able to take hundreds of hours of work out of the solution, your technology will be out of date before the car even looks like a car and there is no way to design for what has yet to be discovered. Unless you somehow have a way of building it really quick, you might find it a project that never gets anywhere.
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Old 11-20-2007, 08:24 PM
zibko zibko is offline
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Default Re: Building from the ground up.....

Thanks for sharing your dream list David. Why to try reinventing the wheel? Most of cars these days are nice already. Variety is here and everyone can find something to suit needs or budget at the moment of purchase. The only part we do not like is IC engine.
What is the point of building whole car from scratch anyway? There are few corporations on the planet doing that for decades. Letís concentrate instead on what they can not or don't want to do so far - long range EV.
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Old 11-20-2007, 08:37 PM
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Default Re: Building from the ground up.....

Greenflight,

thanks for posting that link. In fact I have seen that website before, and while I am not a fan of 3 wheelers, their XR-3 hybrid is an impressive car none the less, and I recomend anyone interested in this topic check out that website.

Some basics about the XR-3

Air bag suspension, and I think it is Awd (2 front wheels are diesel, single rear is electric)

foam/composite construction, mainly hand carved (eeeeek, lots of messy work) ontop of of a steel "tunnel" frame (extremely strong, but still very light).

Diesel engine in the front, and electric powertrain in the back (this is a parrallel plug-in electric hybrid)

1300 lbs curb weight (very nice)

125 MPG with diesel power alone, up to 225 with mixed diesel electric driving (this is their claim, so I take it with a grain of salt, but I think its possible)

If this car had 4 wheels, I would consider buying one, but I might just steal some of their ideas instead.

Here is some info on the diesel engine that is recomended http://www.dieselenginemotor.com/kub...ini/page5.html. But I can't help but wonder why not use a VW diesel, it would have to be much cheaper and get at least as good economy (and more power).

panraran,

I'll just go over some of the basics first.

There are two basic types of hybrids (in theory, either one could be a plug in):

The most comon is parrallel, this is what the prius and insight use. Usually, it is an adaptation of a conventional powertrain, such as the addition of an electric motor/generator to an automatic transmission that can give what the industry calls "launch assist" as well as some Regenerative Braking. This setup rarely results large improvements in fuel economy, because all of the same moving parts that the car would normally have are still there, like the automatic transmission, and in the case of the prius, the electrics basically do nothing once on the highway (this is why the WV TDIs get better MPGs). By toyota's example our 1956 fergason tractor is a hybrid, becuase it can propel itself a few feet with the starter (no neutral safety switch).

The other kind is the series hybrid, the chevy volt is supposed to a series hybrid (I'll believe it when I see it, after seeing what GM did to the EV1). A series hybrid is basically an all electric car that has a genset built into it. This has the advantage of getting rid of many of the heavy moving parts of a parrallel hybrid (transmission, driveshaft, and possibly even the differential). In this configuration, the batteries are always powering the electric motor, which is always driving the car by itself. When the battery runs low, the generator kicks in and keeps you going. This allows you to get away with a smaller (hopefully more economical) ICE to run the generator, which no longer has to propel the car up steep inclines or up to speed at the onramp. In theory, this car can also double as a backup generator for your house. I preffer series .

A simple way to think of the difference betwwen series and parallel, is that series is based on a pure electric car, a series is based on a ICE powered car.

In theory, any electric car can be converted to series hybrid, the trick is finding a powerpland compact enough that can still meet the cars average Hp requirements.

EricN,

I would be very interested in learning more about your project. I have some experience with polyester and glass fiber, but never tried something as big as this before. How did you get the shape? the GT40 is not an easy shape to make from scratch.
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