[Richard Henry]

Amen! I keep telling people that, and they look at me like I'm some
kind of idiot.

You have also told us how you like to drive your big import illegally
fast and tried to rationalize it by claiming that among the vehicle's
luxury features is that it runs more efficiently at high speed.

 

[Jim Thompson]

You have also told us how you like to drive your big import illegally
fast and tried to rationalize it by claiming that among the vehicle's
luxury features is that it runs more efficiently at high speed.

I didn't rationalize anything. However I do agree that leftist
weenies should be taxed more heavily to support my excesses ;-)

And I certainly have no problem with YOU driving a tin can, just NOT
my children and grandchildren ;-)

...Jim Thompson

 

[David L. Jones]

Is it not about time that we saw more hi spec electric cars on our
roads. I saw the Tesla Roadster and it outperforms a Ferarri on
acceleration but what of teh charging time. Can we now re-charge in
say 10 mins? The overnight charge is impractable unless the car is to
be used for short distances from home.

It can be made reasonably practical. I know someone who modified a
small car into a fully electric car, even placed the mains plug for
charging under the old petrol cap. Drives it to and from work and can
plug it into an outside socket on the wall at work to let it charge
for 8 hours.
A local shopping center even has a dedicated space for an electric
vehicle to allow recharging.
Max range is about 50km which is not that great, but enough to get to
and from work, shopping, or across the city (Sydney).

And no, you can't recharge in 10 minutes.

I like the new electric scooters and bikes, very cool.

Dave.

 

[Richard Henry]

I didn't rationalize anything. However I do agree that leftist
weenies should be taxed more heavily to support my excesses ;-)

And I certainly have no problem with YOU driving a tin can, just NOT
my children and grandchildren ;-)

OOHH!. Think of the children...

You sound like a leftist weenie.

Please explain again the more-efficient-at-higher-speed feature.

 

[krw]

OOHH!. Think of the children...

You sound like a leftist weenie.

Not at all. Not "the" children. *HIS* children. There is a
difference.

Please explain again the more-efficient-at-higher-speed feature.

It's entirely possible as was explained at the time.

 

[John Larkin]

OOHH!. Think of the children...

You sound like a leftist weenie.

Please explain again the more-efficient-at-higher-speed feature.

If your time is worth a few hundred bucks an hour, it's inefficient to
drive slow.

John

 

[MooseFET]

OOHH!. Think of the children...

You sound like a leftist weenie.

Please explain again the more-efficient-at-higher-speed feature.

His fuel line leaks badly. Every minute the engine is on, it looses a
gallon,

 

[David L. Jones]

"default"



** The Roadster has a recharge time ( from dead flat ) of 3.5 hours -
according to the makers.

Only thing is, owners need to have a dedicated, 3 phase power outlet
available at home with a capacity of 15 kW - then it will costs about
$10 or so in electricity for a full recharge.

However ..............

- just load the boot (ie trunk in the USA) with a bunch of these babies
and get it done in only 1 minute !!!!!

http://www.dcviews.com/press/Toshiba-One-minute.htm

"A prototype of new battery (a laminated lithium ion battery with
600mAh capacity) was discharged and fully recharged 1,000 times at a
temperature of 25 degrees centigrade and lost only 1% of capacity
during the test."

Damn, that's good. I wonder how many cycles they actually get before
it starts to lose some real capacity?

Dave.

 

[Richard Henry]

Not at all. Not "the" children. *HIS* children. There is a
difference.


It's entirely possible as was explained at the time.

It was bs then and it's bs now. All fancy gearing and ignition tricks
will be overcome by the inevitability of the non-linearity of increase
of air resistance with speed.

 

[Glenn Gundlach]

Much of the energy required for acceleration is recoverable upon
deceleration via regenerative braking. It's just a question of

efficiency.

The amount of kinetic energy is related to the speed, not the
acceleration. If you accelerate more rapidly, that extra energy is
not recoverable. Modest acceleration is less wasteful.

The inevitable losses are friction and air resistance, primarily the
latter, especially at high speeds. For stop-start urban driving, failure
to recover kinetic energy upon deceleration (i.e. lack of regenerative
braking) is a significant efficiency loss.

Realistically, we aren't going to see electric vehicles becoming
widespread until battery (or equivalent energy storage) technology
improves.

Taxis and buses are a different matter. For heavy use in an urban
environment, the efficiency gain from regenerative braking could make it
worthwhile developing the necessary infrastructure (i.e. places where you
can swap flat batteries for fully charged ones every couple of

hours).

Got a Prius last year. So far 52+ mpg for 15000 miles. It's the best I
can do.

GG

 

[Phil Allison]

"Glenn Gundlach"

The amount of kinetic energy is related to the speed, not the
acceleration.

** Correct.

If you accelerate more rapidly, that extra energy is
not recoverable.

** Shame how that flatly contradicts your first statement.

Fact is, there is no extra energy input.

Simply a larger power input applied for shorter time.

Modest acceleration is less wasteful.

** Maybe so, in practice, with typical internal combustion engines - but
not for any simple physics reason.




....... Phil

 

[John Larkin]

It was bs then and it's bs now. All fancy gearing and ignition tricks
will be overcome by the inevitability of the non-linearity of increase
of air resistance with speed.

The air resistance is highly nonlinear, cubic power:speed roughly,
whereas other losses are essentially independent of speed. Every car
will have an optimum speed for miles/gallon, and it won't be zero.

John

 

[MooseFET]

The air resistance is highly nonlinear, cubic power:speed roughly,
whereas other losses are essentially independent of speed. Every car
will have an optimum speed for miles/gallon, and it won't be zero.

It also won't be much over about 50MPH. It takes about 15 HP to push
a modest sized car at 50MPH. The windage losses per mile run as just
about the square of the speed.

 

[Jim Thompson]

OOHH!. Think of the children...

You sound like a leftist weenie.

Please explain again the more-efficient-at-higher-speed feature.

I don't ever recall saying "more-efficient-at-higher-speed".

But I guess it WOULD depend on your definition. The engine is
optimized right around 3000RPM (85MPH), but external drag is higher.

...Jim Thompson

 

[Jim Thompson]

On Mon, 30 Jul 2007 20:02:28 -0700, Richard Henry
[snip]

Please explain again the more-efficient-at-higher-speed feature.

If your time is worth a few hundred bucks an hour, it's inefficient to
drive slow.

John

There ya go ;-)

...Jim Thompson

 

[Guy Macon]

I don't ever recall saying "more-efficient-at-higher-speed".

But I guess it WOULD depend on your definition. The engine is
optimized right around 3000RPM (85MPH), but external drag is higher.

Assuming that "optimized" means maximum efficiency as opposed
to maximum power or torque, wouldn't it be more efficient at
3000 RPM in first gear?

Part of me thinks about the far lower drag and says that it
would. Part of me thinks about those pistons moving up and
down more times per mile and sucking in about the same amount
of fuel per cycle and says that it wouldn't. Maybe it needs
an engine sized for 3000 RPM in first gear to make it work?

Also, I can't prove it, but I suspect that hard accelerating
to some speed (don't know how fast) and then shutting down
the engine and coasting down, then repeating, gives the
maximum fuel economy.

 

[John Larkin]

Assuming that "optimized" means maximum efficiency as opposed
to maximum power or torque, wouldn't it be more efficient at
3000 RPM in first gear?

Part of me thinks about the far lower drag and says that it
would. Part of me thinks about those pistons moving up and
down more times per mile and sucking in about the same amount
of fuel per cycle and says that it wouldn't. Maybe it needs
an engine sized for 3000 RPM in first gear to make it work?

Also, I can't prove it, but I suspect that hard accelerating
to some speed (don't know how fast) and then shutting down
the engine and coasting down, then repeating, gives the
maximum fuel economy.

Interesting curve:

http://www.fueleconomy.gov/feg/driveHabits.shtml

And it is reasonable to also factor in the value of your time.


John

 

[Jim Thompson]

Interesting curve:

http://www.fueleconomy.gov/feg/driveHabits.shtml

And it is reasonable to also factor in the value of your time.


John

"Remove excess weight"... don't give a leftist weenie a ride ;-)

...Jim Thompson

 

[Charlie Edmondson]

MooseFET wrote:




That's a very sensible idea actually. The recharging rate could be dynamically
modulated to provide a full charge quite quickly whilst at the same time
minimising peak load on the grid (and obtaining optimal use of spare capacity) .
That'll keep the power generators very happy indeed.

Plus, you're presumably get a discount for plugging it in earlier rather than
later. That might provide the required incentive to do that.

I'd patent it FAST.

Graham

Also, it isn't like 10 million cars will suddenly appear overnight, they
would be added over a period of many years. During this transition,
power companies will slowly be building up the grid, esp. in areas that
have more electric vehicles...

Charlie

 

[MooseFET]

Also, it isn't like 10 million cars will suddenly appear overnight, they
would be added over a period of many years. During this transition,
power companies will slowly be building up the grid, esp. in areas that
have more electric vehicles...

The power companies can't be counted on to build up the grid.
Spending on new stuff would cut into this months profits. If it
doesn't look like the grid will support it, people won't buy the
cars. When people don't buy the cars no new grid is needed.