Re: SRAM or nuvinci electric pedal asssist

On Tue, 23 Dec 2008 15:15:22 GMT, Peter Cole <peter_cole@xxxxxxxxxxx>
wrote:

carlfogel@xxxxxxxxxxx wrote:
On Tue, 23 Dec 2008 03:50:16 GMT, Peter Cole <peter_cole@xxxxxxxxxxx>

I wouldn't expect "fair & balanced" coverage from the mouthpiece of the
American Enterprise Institute.

The

Dear Peter,

What do you see as unfair or unbalanced in this section about the
Tesla's shortcomings?

Why restrict my critique to one section of the article?

But just to respond to that, first read the primary source article:

http://www.edmunds.com/insideline/do/Drives/FirstDrives/articleId=124716


"We may earnestly speculate about flywheels and compressed air and
various gases, natural and unnatural?but we go with gasoline.Right now
the impressive Tesla electric roadster is the darling of the
automotive press. Its beguiling style and cutting-edge technology have
made it a sensation, albeit an expensive one, at close to $100,000 a
copy. Instead of conventional lead-acid batteries, or nickel
metal-hydride (NiMh) batteries such as those that are used in the
Toyota Prius hybrid, the Tesla draws its energy from an elaborate and
sophisticated array of 6,831 interconnected lithium-ion batteries?the
kind used to power top-line laptops. These batteries, each a little
bigger than a common AA alkaline, are immersed in a liquid cooling
system to prevent them from becoming too hot and possibly bursting
into flames when under the stress of feeding a total of 375 volts to
the Tesla's electric induction motor."

The text from the test drive article:

"The magic lies in the battery pack. There are 6,831 lithium-ion
batteries, each about a third bigger than the AA cells you use in your
digital camera. They're linked together in a unique package that
incorporates liquid cooling, safety fuses and fancy power control
programming to eliminate worries about what battery engineers like to
call "thermal events." The batteries feed 410 volts to the Roadster's
air-cooled AC induction motor, which redlines at 13,000 rpm."

Note the amplification of the hazard "possible bursting into flames when
under the stress..."

"Enthusiasts see the Tesla as the 'I told you so' electric car, with
its world-class acceleration (a reputed 0 to 60 mph in 4 seconds), a
top speed of over 120 mph, and a claimed range of 220 miles. But that
range will bear some scrutiny in real-life conditions as Teslas start
getting into the hands of owners. Automotive testers are already
sounding some warning bells. John O'Dell, who test-drove the car for
Edmunds Inside Line, notes that its range may be 'more like 180 miles
if you like to goose it every once in a while and down around 150 if
you regard speed limits as mere suggestions.' In other words, if you
drive it like a sports car (which it is) you will experience a steady
deterioration of performance as you drive. Add the weight of a
passenger or the challenge of a curving road through hills and the
downturn is more pronounced. O'Dell observes: 'The quickest your
electric sports car will be is in the first few minutes after you
leave the garage. It just gets slower after that until you return home
again.'"

What the reviewer said was substantially different.

"We drove the Tesla Roadster hard all morning, and by the time we got
back to flat ground for our official instrumented acceleration run, we
had only about an eighth of a charge and nine miles of range left in the
battery pack. At this point, the Tesla's electronics are programmed to
kick into a torque-limiting, energy-saving mode when the batteries have
been drained significantly."

"Fortunately we were able to add a bit of juice with an hour's stopover
in Tesla's shop, hooked up to the 70-amp, 240-volt home-charger unit
that comes with each car (installation extra). But we still had only 23
miles on the range meter and a severe case of torque restriction when we
headed out to the lightly traveled highway that serves as Tesla's
unofficial test track for acceleration runs."

"Add damp street surfaces and a slight uphill grade and the best 0-60 we
were able to record was 6.0 seconds."

But, earlier in the article:

"Our test car was outfitted with the jury-rigged tranny Tesla is using
so it can get cars into production pending the introduction of a new
single-speed transmission and reconfigured motor ? a system the company
is calling powertrain 1.5.

With the taller 2nd gear our only option, we didn't get the 3.8-second
0-60-mph acceleration that some people have reported, or the 4.4 seconds
that Tesla's own testers have recorded. But with a full charge early in
the day, the pace felt close to the 5.7 seconds the company says the
initial one-speed production models will achieve."

So, to summarize, the "deterioration of performance" that the American
Enterprise article highlighted, was 5.7 to 6.0 sec 0-60, with the
additional handicap of damp road & slight uphill. OK, big deal.


"Make no mistake?the Tesla is an impressive performer, praised for its
handling, its responsiveness in tight spots, and its rocket-like
acceleration. It is often compared to a Porsche 911. Okay. Let the
Porsche drag with the Tesla a few times. The Tesla may well reach 60
mph slightly faster than some versions of the 911. But, while the
Tesla's batteries are electronically panting and cooling off and its
dash displays are flashing warnings about decreased range and
automatically restricting the electric motor?s torque, the Porsche
will go merrily on its way and cruise up to 400 miles on the remaining
gasoline in its 17.7 gallon tank."

Never mind that the Porsche will also be "panting and cooling off" after
a few drag races, this predicts the Tesla will be in torque restriction,
but, other than low battery state (which shouldn't happen after a "few
drag races"), I don't see the basis for that prediction, and even if it
is true (for thermal reasons, for example). The performance hit seems
modest according to the test drive results.

So, the performance of the two is comparable, and the Porsche has a best
case range of 400 mi, the Tesla 225 mi. The price of the Tesla is
emphasized, while that of the Porsche is omitted. FYI, if the 911 is a
turbo, 2008 MSRP is $126-136K.


"And while the Tesla is recharging its batteries over a period of
hours, the Porsche can have its tank refilled in a minute or two and
be on its way. The electrically refreshed batteries in the Tesla will
then begin another cycle of diminishing performance, while the
gasoline in the Porsche's tank will give it optimum performance to the
last drop.

Again the emphasis of this "diminished performance". To call this
misleading would be charitable.


For all its technological edginess, the Tesla is really
just another example of why gasoline is still king.

No, it's really an example of how an electric car can compete today at
the performance high-end, with the only real caveats being range and
refuel times. For many owners/applications those issues won't be show
stoppers, but the reason I originally posted on this thread was to
discuss the possibility of ultracapacitor technology to ameliorate these
issues. It is not the only interesting technology, lithium cell
technology is relatively young, especially compared to IC
engine/drivetrain technology.

After all the
promises of their yesterdays, electrics remain the cars of tomorrow
because no battery or combination of batteries has duplicated the
energy density of a gallon of gasoline."

This is probably true, but is not really the issue (energy density). The
real issue is to get energy density (including lifetime costs) good
enough to compete with hydrocarbon fuels. For some applications, that
day is already here, for many others it seems within sight.

The real benefit is "well to wheel" efficiency, something the article
doesn't even mention. Check out:
http://www.teslamotors.com/efficiency/well_to_wheel.php
for a comparison. The Tesla roadster is 2x the Prius.

But this is only a rebuttal of your cherry picking of a cherry picking
article. The article is loaded with other biases. The most glaring is
comparing (unfavorably) an actual test driven electric car (albeit a
Lotus-type sports car) against a hypothetical "concept car" of a more
pragmatic sedan configuration.

From the A E article:

"The cars we drive may be more Prius-like in one sense, mating the
virtues of electricity and internal combustion, but they will very
likely be larger and more powerful than a Prius. The cars of a decade
from now may be more like the Mercedes-Benz F700 research car now being
tested. It?s a big car, as big and roomy as the present S-Class Mercedes
flagship sedan. The F700 can accelerate from 0 to over 60 mph in 7.5
seconds and has a top speed of 120 mph, but it averages 44 miles per
gallon and has a very clean exhaust."

Sure, we'll all be driving Mercedes, big ones, too! (S-class, no less!)

From another, perhaps more realistic, source:

http://www.cars.com/go/features/autoshows/vehicle.jsp?vehicletype=concept&autoshowyear=2008&vehicle=concept_mercedes_f700&make=Mercedes-Benz&model=F700

"The F700 isn't a hybrid, though ? it uses a super-efficient
four-cylinder engine with a prototype powertrain that moves like a V-6
but gets a dreamy 44.3 mpg.

Remember this is a concept, so those numbers aren't even close to being
real yet."

More on the engine/car at :

http://www.gizmag.com/go/7679/

"The result is an 1800cc four-cylinder motor producing 238 bhp (175 kW)
with torque of 400 nm while delivering 6 l/100 km (47 UK mpg, 40 US mpg)
in an S-class."

The problem is we don't need 40 mpg vehicles, we need 100-200 mpg
vehicles. Internal combustion engines just won't get us there.

Dear Peter,

Er, you picked the Tesla as your example in your original post.

And the slower acceleration was after they stopped for an hour's
recharge, according to what you quoted.

You noticed the range and refuel problems--what about the $100,000
price tag?

And what about the manufacture of the batteries, the ability of the
electrical grid to recharge them all (California already has rolling
blackouts in the summer), and the cost of that electricity (apart from
the "fuel", someone has to pay the tax for the roads).

Last I heard, gas is $11 a gallon in Italy, with no swarms of electric
cars in sight.

The problem is that someone decides is "needed" isn't the same as what
actually works on a large scale.

Cheers,

Carl Fogel
.