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Captain Hybrid

Tesla's CEO: 'Half of Cars Will Be Electric in 15 Years'

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Rob Spiegel
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Re: electric cars and sales
Rob Spiegel   8/31/2012 4:44:50 PM
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Akwaman, do you know how long the wait is? I would imagine that would make a big difference. I'm not sure how it works with EVs, but a recent L.A. Times story reported that only 25 percent of hybrid owners purchased a hybrid when they bought their next car.

akwaman
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electric cars and sales
akwaman   8/29/2012 2:05:47 PM
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Electric cars are not sold like other cars.  You have to order them ahead of time.  We are Americans, and we know we want everything NOW.  So when someone goes into a dealership, can they drive off with a LEAF or a VOLT?  NO.  This is the main reason that sales are lackluster in my opinion.  If they were in the dealerships, looking pretty and letting people test drive them and take them home, I feel that things would be different.  People who have these electric cars love them.  If you have one and don't, please post, I have never heard any complaints by owners.  Only responses I hear are positive, and they wouldn't give them up for the world.

Rob Spiegel
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Re: electric cars
Rob Spiegel   8/27/2012 12:26:10 PM
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Wow, Chuck, that is suprisingly low. And such a dip in one year. I don't see how they can make a profit on such a low volume of sales.

Charles Murray
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Re: electric cars
Charles Murray   8/24/2012 5:09:49 PM
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Actually, the Nissan Leaf is in a sales slump. Only 395 sold in July, down from 931 in July, 2011 (which is not a very big number, either).

Rob Spiegel
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Re: electric cars
Rob Spiegel   8/23/2012 11:48:34 AM
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That must be a California phenomenon, Jsmith14. Overall, the sales on EVs and hybrids is not nearly so high.

Rob Spiegel
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Re: Efficient gas engines
Rob Spiegel   8/20/2012 12:56:45 PM
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Kevin, your first point actually answers a question I posed ealier in this discussion: Is the return motion in the pistion cycle actually inefficient? That seems to be the question that Mazda's engine was supposed to answer. Yet, if the return motion of the piston is not inefficient, the rotary engine arguement loses its power (so to speak).

Kevin
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Re: Efficient gas engines
Kevin   8/20/2012 12:50:16 PM
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Rob & ChasChas,

I hope I don't come across as too strident with this input - but you are completely mistaken about the relative benefits of piston and rotary engines vs. efficiency.  To be kind, I'm guessing you guys are electrical engineers...not mechanical ?  I've studied engines and efficiency and alternative energy my entire life...and I'll just say that there is a lot of mis-information out there on these subjects.

Here's a salient bullet list:

1.  There is no efficiency disadvantage to reciprocating motion, contrary to Mazda's (excellent marketing, but technically incorrect) promotion of their rotary engines.  The crank / flywheel system stores any energy used to decelerate the piston at the end of a stroke and uses it accelerate it during the next.

2.  The main issues regarding engine efficiency or lack thereof have to do with the GAS PROCESSES, HEAT FLOW, FRICTION.  In other words - the engine is a device that performs thermodynamic processes on the gasses, and those gasses don't really "care" if the motion is reciprocating, rotary, or even flow-based (like jet turbines).

3.  Wankel engines are wonderfully compact for their displacement, but they are fundamentally less efficient than a piston engine for several reasons: the shape of the combustion chamber at TDC is long-and-thin.  This creates a high surface area for which the combustion heat escapes.  Look at the size of the radiator on a Mazda rotary car - you'll be amazed that it is as large as a V-6 engine, even though the engine is tiny.  Also, the continuous rubbing of the apex and side seals of the rotors has higher friction than the equivalent round piston rings.  An interesting fact (that even Mazda apparently does not know, or at least did not want to advertise) is how to calculate the "equivalency" between a wankel and a piston engine.  An RX8 engine is equivalent to a 3.9 liter V-6, but with a 1.5:1 STEP-UP gear ratio (out of the engine).  If you look at the Horsepower/Torque chart, and adjust RPM downward by 1.5X & Torque upward by 1.5X you'll see a characteristic that looks like a very average (perhaps sub-par) naturally aspirated engine of 3.9 liter displacemnt.  The legendary high rpm and power of wankels are an illusion, and (as any rotary owner knows...I have owned 2) the MPG is not good.  This, plus poor HC emissions (also caused by the combustion chamber shape) is why GM scrapped their $1.5B rotary engine factory, and Mazda only "limps forward" as the only major wankel car.

4.  The optimum combustion chamber shape from a perspective of heat loss is hemispherical - which coincidently results from a piston engine!  Even better is a dual-opposed piston engine like the OPOC (see: http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder/  ).  Note that the most direct way to higher efficiency is to expand the combustion gasses more fully ...which is what Atkinson engines do.  That's why this type of engine is used in the Prius and Camry and new Fusion hybrids. 

5.  There are other enhancements to efficiency in new piston engines - offset crank to reduce friction, GDI (Gasoline Direct Injection) to improve fuel metering and combustion, etc.  Of course, engine downsizing (smaller engine, but turbocharged to get required power when needed) help cruising efficiency.  Today's best engines are more efficienct than the EV zealots would have you believe - the current Prius engine is 38% efficient and they are working on a 42% version.  This is actually as high or higher than the BEST coal-fired power plants.

cheers,

Kevin

William K.
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Platinum
"half of the cars will be electric"
William K.   8/17/2012 2:34:45 PM
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What else could the CEO of an electric car company possibly say? Expressing any other belief would hurt the stock values and reduce the earnings, and the shareholders would have him out on the street in a few hours. 

Remember that the CEO is only responsible to the board and the shareholders, and that whatever else they do will be excused, as long as it boosts share prices. With that in mind, we should also evaluate the assertion in light of the quantity of power needed to replace the fuel consumed by a half of all cars. WE would quickly realize that it is quite a large amount. Next comes the question about where all of this additional electric power will come from, and how it will be distributed to those who need to recgarge their cars. 

If we can come up with workable answers to those questions then possibly there could be some validity to his assertion, but if we are not able to come up with good answers, then back to the first paragraph. What else COULD he possibly say?

Rob Spiegel
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Re: Efficient gas engines
Rob Spiegel   8/14/2012 9:48:41 AM
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I agree, Chuck. I would bet they're working on it now. There are plenty of reasons beyond the government mandate. For one, it's a competitive factor.

Charles Murray
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Re: Efficient gas engines
Charles Murray   8/13/2012 10:53:20 PM
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In answer to your question about whether the piston engine is already efficient enough, Rob...I'll bet automakers find more efficiencies after the 54.5-mpg bill is signed into law.

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