Tesla Motors

[The Toecutter]

I practically creamed my pants looking at that body. God damn, if that were a woman, I'd hit it!

Ok, in all seriousness, this was the proper route to go. Tesla does not have the capability to mass produce. That would take $200+ million in machine tools and crash tests. Only the major automakers have that money(as we know, the major automakers refuse to mass produce electric cars).

No one is going to pay $80k for a 5-seater family car that does 0-60 in 9 seconds, when they can buy a Corolla for $15k, even if that $80k car were electric.

Will they pay $80k for a 2-seater supercar that does 0-60 mph in 4 seconds? Yes.

Tesla has the right strategy.

The technology is there to mass produce an electric car with 200+ miles range, 0-60 mph in < 9 seconds, 110 mph top speed, and ability to seat 5 adults. It's been there for a decade. BUT, that requires mass production. The big automakers are the only ones who can mass produce, and they refuse to make electric cars. Period. Tesla motors cannot yet mass produce. They would do it if they had the economies of scale, believe me. So would AC Propulsion, Commuter Cars, and others.

the range kinda sucks...

Same range as many gas cars, really.

80-100k ???

holy shnikees
you know how much f'in gas that is...???
hmm

my car is say $3000
a difference of about $87k
thats 29,000 gallons at $3.00/gal
even at 30mpg thats 870,000 miles !!!!!!!
PAAAAALEEEEEEZEEE!!!

thats so uncool
thats stupid
i'd shoot anyone i see driving one
f'in idiot

a) It's a sports car, not a family car or errand runner. It's not made to save money.
b) That gas car is ~$.03-.08/mile in maintenance depending on what it is(Hondas and Toyotas at the lower end, Ford or GM at the upper). Even factoring in the battery pack, this car is certainly cheaper to run than a Corvette or similar sports car.

If you want a $10k electric car, there's always the Zap Zebra in the US, or the REVA in England.

**** that. $10k for a hand-built golf cart?

If you want an eelctric car for $10k, build it. You could get much better results that way, 0-60 mph ~5-6 seconds, 130+ top speed, and 60-80+ miles range is doable for that amount of money. But only if you build it yourself.

Just wait until alot of people start pluging in and the grid go's down.

Most charging is going to be done when the car is not in use, usually at night. When the grid is not seeing peak use, it tends to have 40-60% of capacity freed up. We could handle many tens of millions of pure electric cars charging during those times without a problem.

As to the amount of electricity consumed, according to the CIA World Fact Book, the U.S. consumes about 3.7*10^12 kWh of electricity per year from the outlet. A midsize electric car sized and shaped like a Ford Taurus or a small SUV like a RAV4, with no attention to aerodynamic efficiency, will use about .3 kWh per mile from the batteries, about .4 kWh/mile from the outlet. Typical car in America sees 12,000 miles/year of use. America has 220 million cars.

Do a little number crunching on how much electricity consumption would go up if all cars were electric.

With a grid that often has lots of available capacity during off peak, wouldn't even make a dent.

Now recrunch the numbers for a full size EV with low drag coefficient around .16, say, sized like a Ford Crown Vic and needing .2 kWh/mile from the outlet, or .15 kWh/mile from the batteries.

[JanGeo]

Originally Posted by The Toecutter

Ok, in all seriousness, this was the proper route to go. Tesla does not have the capability to mass produce. That would take $200+ million in machine tools and crash tests. Only the major automakers have that money(as we know, the major automakers refuse to mass produce electric cars).

From ETLIST:

"The roadster is designed and built by Lotus in the UK and will be sold in California, Chicago, New York and Miami starting next year, with prices reported to be in the $80,000-$120,000 range. Hot on the heels of the ?Who killed the electric car?? documentary, as well as the recent launch of the electric Smart For Two, interest in electric cars is once again rising."

No manufacturing??

And I thought it looks like a Ferrari - it's a Lotus! DUH!

[The Toecutter]

I could be wrong, but isn't the chassis is produced by Lotus, and not the entire car and drive components itself(The latter by Tesla Motors)?

Tesla Motors itself has said that it would love to sell a $50k four door car(likely a sort of luxury sedan), dependent upon the success of the Tesla Roadster to raise the funds.

If Lotus has 100% of the say in control, design, and manufacturing, they'd be able to do it already.

[JanGeo]

Probably a little easier to mass produce a $80,000 car than a $6000 Vectrix motor scooter. And since they are only 3 years old they should not have wasted all the raised capitol like Vectrix did over the past 9? years?

[JanGeo]

http://video.google.com/videoplay?do...85113933785378

Interesting commentary about where the money GOES....

[The Toecutter]

"...all free cashflow goes completely into driving the technology to lower costs and make it more available..."

Yep. They'd like to get a mas market EV on the road for common folk. It can be done. Someone willing to do it just needs the money.

[omgwtfbyobbq]

I'm kinda dissappointed they didn't make it smaller, 250miles@70mph woulda been nice. I wonder how many people will get stranded because the range drops to ~150miles@75mph?

[The Toecutter]

Even given that aerodynamic drag varies as a square of velocity, the change in range from 70 mph to 75 mph wouldn't be that dramatic. If it gets 250 miles at 70 mph, it would get around 220 miles at 75 mph. This of course neglects cross winds and such.

The designers really didn't pay much attention to aero. The drag coefficient of the Tesla probably isn't drastically better than the Elise it shares many traits with. I'd guess around .30 for the Tesla, while the Elise has a published .36. But it looks damn good.

With a 55 kWh Li Ion pack and 250 miles range, that's 220 Wh/mile consumed. The GM EV1, weighing 500 pounds more than the Tesla, with a .19 drag coefficient, only needed 140 Wh/mile. If this car would have been done in the body of say, an Opel Eco Speedster, with its .20 drag coefficient and 16 square foot frontal area, while keeping the 2,500 pound weight, range would be 400-450 miles with that pack.

omgwtfbyobbq, do you happen to be a member of peakoil.com forums by chance?(Another member there has your same name) I lurk there, quit posting there when college and in-progress EV took too much time, will again resume posting there shortly.

[omgwtfbyobbq]

Yeah, I have a few names and frequent more than a few boards. And I've been browsing bbs' a bit much since I'll probably have to wait until the end of August before I start work. For the comparison I was refering to the roadster's ~250 miles epa highway rating, which is at ~48mph, so range should be *~150miles@75mph, which will probably result in a couple strandings due to extended high speed highway driving. The 250miles@70mph is what I think they should've built, but something that looked too small and too streamlined probably wouldn't have appealed to their target as much as a sportscar looking vehicle that's still faster and more efficient than anything in it's price range. They may have to move away from people's perceptions of EVs, but they can't run from physics forever!
Speaking of your EV project, hows it coming?

*75^2/50^2=~2.25, which will probably be less than half, but I'm giving rolling losses the benfit of the doubt.

[The Toecutter]

Lets estimate the amount of power it needs to maintain various speeds. The following parameters are estimates(guesses):

Weight(W): 2,500 pounds
Drag Coefficient(Cd): .30
Frontal Area(A): 18 square feet
Rolling Resistance Coefficient(Cr): .012 (Assumes sticky, non LRR tires)
Transmission Efficiency(TE): .90 (Assumes wheel bearing losses and other stuff are counted, which is outside the realm of the transmission itself)
Motor Efficiency(ME): .91 (assumes inverter losses as well)
Battery Capacity(C): 55 kWh

Velocity(V): expressed in mph
Force Drag(FD): expressed in pounds
Force Rolling(FR): expressed in pounds
Wheel Power(WP): expressed in horsepower
Motor Power(MP): expressed in horsepower
Battery Power(P): expressed in kW
Range(R): expressed in miles per charge

I will use the following equations to estimate how the car will behave:

Equations used:

FD = .002558 * Cd * A * V^2
FR = Cr * W

WP = (FD + FR) * V / 375
MP = WP / TE
P = MP / ME / 1.35

R = C / P * V

Results:

At 48 mph:

FD = 31.83
FR = 30
WP = 7.91
MP = 8.79
P = 7.16
R = 369

At 70 mph:

FD = 67.68
FR = 30
WP = 18.23
MP = 20.26
P = 16.49
R = 233


So range at 48 mph is estimated at a very high 369 miles. Way over the EPA cycle. Obviously, my calculated result is incorrect, as Tesla or the EPA did not claim such high range. Thus one or more of the following explanations may be correct:

a) The EPA highway cycle isn't a constant speed of 48 mph, and thus energy taken for repeated accelerations and the limited recovery of energy while braking eats into range significantly
b) The electric motor is operating at a less efficient level at these low speeds
c) The range Tesla/EPA claims was obtained with accessories running, such as heat or a/c, or obtained with the top down where aero drag would be highest

The above may or may not be true. I'd need to know the gear ratios to figure out 'b'(Motor/inverter efficiency data available on AC Propulsion's website), and the driving cycle for 'a' can probably be found on the EPA website.

The estimate at 70 mph makes much more sense.


If the 250 mile range is really obtained at a steady 48 mph, this car would be consuming 220 Wh/mile at 48 mph. This is astronomically high consumption for an EV. I know of 5,200 pound pickup truck conversions with no aero mods that consume 225-250 Wh/mile at a steady 50 mph, around 350-400 Wh/mile at 60 mph. For a small sports car to match a pickup in energy consumption, a pickup with over double the weight and far higher frontal area, would be almost laughable.

But hey, stranger things have happened. Failing explanations 'a', 'b', and 'c', maybe the Tesla Roadster has a high .65 drag coefficient. It sure doesn't appear that way and there is talk of it being more aerodynamic than the Elise(.36 Cd), but who knows?

Looking at it from a mathematical standpoint, it would probably need to be going a bit above 60 mph to get under 250 miles range. Lithium batteries are unaffected by Peukert's losses, so no significant(in regard to range) diminished capacity with increased draw.