
Driving Range for the Tesla Model S Family - brbcoding
http://www.teslamotors.com/blog/driving-range-model-s-family
======
portman
The most under-reported aspect of driving a Tesla is how severely topography
impacts range.

Under normal conditions, I use 350 Wh/mi (watt-hours per mile). This is 17%
more than "rated range" because -- and this is a technical term -- I drive
like a madman.

However, when driving to Tahoe (7000 feet higher), I end up using _850_ Wh/mi:
over 2x higher electricity consumption, because mountains.

All this talk of tires and wind resistance is a red herring for topography,
which does more to limit/extend range than any other factor.

What's more, this could be so easily addressed with software: when I input my
destination into GPS, the car should tell me my expected range. It knows the
topography. Use the force, car!

Taken one step further, since Tesla is constantly transmitting telemetry to
home base, Tesla HQ likely knows the average battery consumption of __all
other drivers __who have ever driven that route. This would allow non-
topographical variables (traffic lights, potholes, road conditions) to be
factored into the range calculation as well.

Edit: Mistakenly used kWh/mi instead of Wh/mi units. Hat tip to Tarrosion for
the correction.

~~~
Tarrosion
> Under normal conditions, I use 350 kWh/mi (kilowatt-hours per mile).

Say you get a good rate and pay $0.10 per kilowatt hour for electricity. That
means if you charge your car at home, you're paying $35 per mile to drive.
That doesn't seem right.

Possibly it's watt-hours? That'd be a per mile price of 3.5 cents, which seems
about the right order of magnitude.

~~~
ghshephard
That sounds about right - the 85 kWh battery of the Tesla would then get you
about 240 miles range.

Another interesting way of looking at this then, is that the amount of power
required to power s _single_ 100 Watt Light bulb for 3 1/2 hours could move an
_entire_ Tesla + person inside 1 mile. Wowsa.

~~~
userbinator
"could move an _entire_ Tesla + person inside 1 mile"... on level ground.

If you've ever had to push a car manually in that situation, you'll notice
that it's very easy to keep it moving once you get started, as you only have
to overcome the rolling resistance. I've never pushed a Tesla before but I'd
bet that it's far easier than a regular car, and a regular car isn't that hard
to push already.

According to this page:

[http://physics.ucsd.edu/do-the-math/2011/11/mpg-of-a-
human/](http://physics.ucsd.edu/do-the-math/2011/11/mpg-of-a-human/)

A human walking takes between 100-200Wh/mi, so the Tesla isn't that far off.

~~~
eddieh
> I've never pushed a Tesla before but I'd bet that it's far easier than a
> regular car

Based on what exactly? A Tesla Model S weighs at least 1000 lbs more than
similarly sized cars.

------
MrFoof
Quick note: These ranges probably assume a 100% charge. Although this should
be obvious, _it should be noted that the Model S does not charge to 100% by
default._

By default it charges to 80%. This can be overridden by the user (in
preparation for long trips), though after a few days it reverts back to the
80%. This is the improve the overall durability of the battery -- that is, the
maximum capacity remains higher for longer if the battery is not fully charged
every cycle.

------
Fuzzwah
I tried the range calculator but it doesn't let me compute expected range for
driving 75 mph on a highway on a 120 degree F Arizona summer day.....

Not to mention the 85 mph most people actually sit on.

~~~
mikeyouse
Driving any car at 85mph will nuke the mileage.. DOE figures for 80mph vs.
55mph show a 30% reduction in mileage, so I'd imagine 85mpg is more like a 35%
reduction. Given that MPG isn't a direct linkage, it's worth noting that this
will roughly double your driving cost per mile depending on the car..

[http://www.fueleconomy.gov/feg/driveHabits.jsp](http://www.fueleconomy.gov/feg/driveHabits.jsp)

~~~
nnethercote
You don't have to guess. The linked article has two graphs showing the range
obtained at speeds ranging from 40 mph to 85 mph for different models.

For the 85 KWh battery pack going at 55 mph you'll get about 350 miles of
range. Going at 85 mph you'll just over 200 miles of range. That's slightly
more than a 40% reduction.

------
TrainedMonkey
"the dual motor Model S will quickly torque sleep a drive unit when torque is
not needed and instantly wake it up as the accelerator is pressed to command
more torque."

I can't understand this, is first torque meant to be toggle?

~~~
TD-Linux
Tesla cars use induction motors. The rotors of an induction motor don't supply
their own field, but need to be excited by current in the stator, which
requires power. In addition, once there is a field, it produces hysteresis
losses proportional to the speed of the motor. If the motor is completely off,
the losses from freewheeling are very small.

Cars based on permanent magnet motors do not need to use power to maintain the
rotor's magnetic field. On the downside, the field cannot be shut off, so they
always have hysteresis loss and cannot freewheel as nicely as induction motors
can.

