From: wreck@fmsrl7.srl.ford.com (R. Cage)
Subject: Re: Electric Cars Energy Usage: Summary
Summary: Paying $16,000 for a Tempo left Houtz so broke he can't pay attention.
Organization: Ford Motor Company Scientific Research Labs, Dearborn, MI
Date: Fri, 10 Apr 1992 17:28:43 GMT

In <43520143@hpindda.cup.hp.com> gph@hpindda.cup.hp.com (Paul Houtz) writes:
>A great deal is made of the following calculations, which basically try
>to indicate how many kilowatt hours per mile my car should use, vs
>my own evidence.

No.  I am questioning whether your figures represent the kind
of driving you say it does.  You could easily be cooking your
figures and, given your lack of understanding of physics, never
know it.

>In particullar, Mr. De Armond, Mr. Coffman, and Mr. Cage attempt to put 
>forth the notion that these calculations are based on undenyable physical
>principles, when in fact, there are a considerable number of questionable
>assumptions involved.

Mostly yours.  When we have real-life examples of a vehicle with
a powertrain designed from the ground up for maximum efficiency
(the Ecostar, with a sodium-sulfur battery and inverter/induction
motor rather than chopper/DC motor), which still consumes twice
the energy you claim for your car when travelling 55 MPH, we get
suspicious.  The Escort minivan does not have much more aero
drag than a Tempo.  It uses about .30 KWH/mile.

Given your claimed range and energy consumption figures, my
conclusion is that your typical speed is considerably less
than 55 MPH.  You might peak at 55, but I doubt that you
cruise at that speed.  By reducing your speed, you can cut
your aero drag and energy consumption to what you claim.

>   Okay, let's take this figure.  1.5 kwh/mile.   This is what the 
>   anti-electric crowd would like you to believe as "reasonable".

That's a little high.  1.5 KWH/mile at 60 MPH is a power of
90 KW, or about 120 HP.  If that represents energy consumption
of a big, heavy (3x Tempo frontal area, 5000 lb) vehicle in
stop-and-go driving with no regenerative braking, it might be
close.  It depends greatly on the driving cycle and wind.

It might also be a number cooked up by SoCalEd to justify adding
more generating capacity to the rate base....

Using .30 KWH/mile at 55 MPH, the Ecostar is consuming 16.5 KW
or about 22 horsepower.  That's entirely reasonable.  Your claim
of .15 KWH/mile or 11 horsepower is less than much smaller, more
aerodynamic cars achieve at 55 MPH, and is not plausible.  You
are obviously moving most of your distance at lower speeds.

>   I would be interested in how you came to the conclusion that 15% of
>   the power is lost between the batteries and the wheels.   For instance,
>   you have not even specified what the drive wheel configuration is. 

The drive wheel configuration is irrelevant; front-drives are
more stingy due to lower weight, not reduced losses.  85% is
a reasonable efficiency for a DC motor and gear train.

>   So, you are using the efficiencies of a gasoline engine to
>   determine if the your calculations regarding an electric engine
>   are sensible.   Scientifically speaking, this is total hogwash.

No, he is using the power requirements of a vehicle with a given
body style to determine if the electric engine could be delivering
that much power.  And you wouldn't know science if it bit you.

>Basically, the calculations that Cage, Coffman, et al, have posted in an
>attempt to discredit my figures about my electric car are such a mish-mash
>of assumptions and occaisional fact that they are useless in making any 
>predictions about my energy usage.

We cannot predict your energy usage because it depends on
un-measured variables, such as speed profiles.  You cannot
even tell us the true KWH consumption of your vehicle by
measurement of charger input, because you have not measured it!

> I believe that the results I am getting represent REAL reductions in
> per mile CO2 output and fossil fuel usage, and nothing posted so far
> has successfully disputed my results.

And a Tempo with a 10 HP gasoline, or better yet, diesel engine
would have roughly equal performance and CO2 emissions with
no range limitations.  Believe me, if enough people wanted 10
HP Tempos, Ford would build them.  They'd do wonders for Ford's
CAFE numbers and be profitable if sold at the same price.
-- 
Russ Cage              wreck@fmsrl7.srl.ford.com  russ%rsi@sharkey.cc.umich.edu
  *  When Ford pays me for my opinions, THEN they can call them theirs. *

                           _Bad_ cop.  No donut.
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