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.
Building from the ground up.....
Hybrid Mode
