John Schilling
12-19-2007, 09:33 PM
On Tue, 18 Dec 2007 10:40:20 -0800 (PST), Mark_Reichert@hotmail.com wrote:
>On Dec 16, 4:09 pm, Larry Caldwell <firstnamelastinit...@peaksky.com>
>wrote:
>> In article <fR5QWjGFFVZHF...@nospam.demon.co.uk>,
>> f...@nospam.demon.co.uk (Robert Sneddon) says...
>> There is also the question of a distribution system for all that
>> electricity. The heaviest 240v circuit in my shop has a 50 amp breaker,
>> which has to be derated to 41 amps for continuous service. To translate
>> that to automotive terms, that's 7 horsepower. Assuming perfect
>> efficiency, a 5 minute charge would put 35 horsepower-minutes into the
>> batteries, not enough to get very far. My entire 200 amp residential
>> electrical service would provide 28 horsepower, but that would leave no
>> spare capacity to run the house.
>> The obvious solution is to install a 400 amp electrical service,
>> dedicating half of it to the vehicle, and the other half to domestic
>> uses. Then you would have to rectify the electricity to charge the
>> batteries. I doubt that solid state would be affordable, but a simple
>> AC motor and DC generator should do the job. At current prices, the
>> installation would cost several thousand dollars.
>> I don't know what the efficiency figures would be like, or how many
>> horsepower would be required for average cruising, but call it an hour
>> charging full bore for each hour of cruising time. Call it 2500 KW-
>> Hours per month. At a dime a KWH, that's $250 a month extra on your
>> electric bill, plus the payments on the charging system, plus the strain
>> on public utilities as they build new capacity to meet the additional
>> demand. For the same money, you can buy 100 gallons of gasoline and
>> save the car payments. It might be much worse than that. The last time
>> I looked, the battery charge/discharge cycle was only about 40%
>> efficient, so the actual electricity consumption could easily be double
>> what I just pencilled out. Are you ready for a $500 electric bill on
>> top of your car payments?
>Somehow that doesn't jibe with their claims:
>http://www.teslamotors.com/
>Con, or are perhaps the figures given by you and other here wrong?
As a general rule, anything with a "Tesla" in the name, may reasonably
be presumed a con until proven otherwise.
But, I went and looked. Conspicuously absent from their claims was any
mention of the battery capacity or the charging power requirement, save
a vague acknowledgement that it would have to be "overnight".
They are also a bit vague about how the 200+ mile cruising range is
measured. Note that, right up front, a two-seat runabout with a 200-mile
range has about one-quarter the performance of a standard passenger car.
It might still be useful, but we'd need to know the operational profile
they were using, and the effect of things like e.g. turning on the air
conditioner.
Instead, they wax enthusiastic about their little hot-rod's sprinting
performance. BFD; anyone with a clue knows that electric motors have
amazingly good low-end torque, and any talented amateur can build an
astoundingly fast dragster using ordinary lead-acid batteries and
surplus industrial motors.
But I can pretty much guarantee the Tesla hot-rod isn't going to be
achieving that 200-mile range while breaking 0-60 records at every
start, and if the only way to get to 200 miles is to drive it like
it were a craptacular old three-cylinder Geo Metro; well, I know
where to buy a used Metro for a whole lot less than $100K, which
seats four and burns not enough gas to mention.
Also, they're using lithium-ion batteries. Which, as they rightly
point out, do not have much of a "memory curve". Which, as they never
point out, degrade to uselesness in five years or so whether or not
you ever discharge them. And which are rather expensive. Yes, they
promise to recycle the old ones for you, but I didn't see a price
quote on the "replace old battery pack with new one" service.
So, I'm going with "con" on this one. Not that they're lying, just
carefully not telling us what we'd need to know to make a rational,
informed decision to buy or invest in their product. And if they're
not telling us what we need to know, it's probably not because the
hidden variables have highly favorable values.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*John.Schilling@alumni.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
>On Dec 16, 4:09 pm, Larry Caldwell <firstnamelastinit...@peaksky.com>
>wrote:
>> In article <fR5QWjGFFVZHF...@nospam.demon.co.uk>,
>> f...@nospam.demon.co.uk (Robert Sneddon) says...
>> There is also the question of a distribution system for all that
>> electricity. The heaviest 240v circuit in my shop has a 50 amp breaker,
>> which has to be derated to 41 amps for continuous service. To translate
>> that to automotive terms, that's 7 horsepower. Assuming perfect
>> efficiency, a 5 minute charge would put 35 horsepower-minutes into the
>> batteries, not enough to get very far. My entire 200 amp residential
>> electrical service would provide 28 horsepower, but that would leave no
>> spare capacity to run the house.
>> The obvious solution is to install a 400 amp electrical service,
>> dedicating half of it to the vehicle, and the other half to domestic
>> uses. Then you would have to rectify the electricity to charge the
>> batteries. I doubt that solid state would be affordable, but a simple
>> AC motor and DC generator should do the job. At current prices, the
>> installation would cost several thousand dollars.
>> I don't know what the efficiency figures would be like, or how many
>> horsepower would be required for average cruising, but call it an hour
>> charging full bore for each hour of cruising time. Call it 2500 KW-
>> Hours per month. At a dime a KWH, that's $250 a month extra on your
>> electric bill, plus the payments on the charging system, plus the strain
>> on public utilities as they build new capacity to meet the additional
>> demand. For the same money, you can buy 100 gallons of gasoline and
>> save the car payments. It might be much worse than that. The last time
>> I looked, the battery charge/discharge cycle was only about 40%
>> efficient, so the actual electricity consumption could easily be double
>> what I just pencilled out. Are you ready for a $500 electric bill on
>> top of your car payments?
>Somehow that doesn't jibe with their claims:
>http://www.teslamotors.com/
>Con, or are perhaps the figures given by you and other here wrong?
As a general rule, anything with a "Tesla" in the name, may reasonably
be presumed a con until proven otherwise.
But, I went and looked. Conspicuously absent from their claims was any
mention of the battery capacity or the charging power requirement, save
a vague acknowledgement that it would have to be "overnight".
They are also a bit vague about how the 200+ mile cruising range is
measured. Note that, right up front, a two-seat runabout with a 200-mile
range has about one-quarter the performance of a standard passenger car.
It might still be useful, but we'd need to know the operational profile
they were using, and the effect of things like e.g. turning on the air
conditioner.
Instead, they wax enthusiastic about their little hot-rod's sprinting
performance. BFD; anyone with a clue knows that electric motors have
amazingly good low-end torque, and any talented amateur can build an
astoundingly fast dragster using ordinary lead-acid batteries and
surplus industrial motors.
But I can pretty much guarantee the Tesla hot-rod isn't going to be
achieving that 200-mile range while breaking 0-60 records at every
start, and if the only way to get to 200 miles is to drive it like
it were a craptacular old three-cylinder Geo Metro; well, I know
where to buy a used Metro for a whole lot less than $100K, which
seats four and burns not enough gas to mention.
Also, they're using lithium-ion batteries. Which, as they rightly
point out, do not have much of a "memory curve". Which, as they never
point out, degrade to uselesness in five years or so whether or not
you ever discharge them. And which are rather expensive. Yes, they
promise to recycle the old ones for you, but I didn't see a price
quote on the "replace old battery pack with new one" service.
So, I'm going with "con" on this one. Not that they're lying, just
carefully not telling us what we'd need to know to make a rational,
informed decision to buy or invest in their product. And if they're
not telling us what we need to know, it's probably not because the
hidden variables have highly favorable values.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*John.Schilling@alumni.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *