Monday, July 29, 2013

Driving a Tesla

I got to drive a friend's Tesla this evening.  Actually, it wasn't even his Tesla; his Tesla was in the shop for some buffing / detailing work, so he had a loaner Tesla.  And, of course, they loan the Model S Performance, which will do 0-60 mph in 4.2 seconds.

I have never driven a car with that much power, and frankly, probably never will again.  My current car is a 175 hp 2009 Nissan Altima, and the car before that was a ~110 hp 1998 Subaru Legacy.  The Model S is equivalent to a 416 hp car.  And without gears to shift, the ability to put all that power directly to the wheels -- even from a standstill at 0 RPM -- is mind-bending.  The slight pause that we have all come to expect from traditional engines and transmissions just isn't there, and it keeps dumping torque to the wheels.  The best analogy is that it's like getting launched from an electromagnetic roller coaster.  Except you're driving this one.

I was admittedly a little nervous about driving around the streets in DC for fear of getting cut off or not seeing someone in the slightly-larger-than-I'm-comfortable-with blind spots. (The C-pillar is jagnormous.)  But all worked out okay in the end, and I had a fun drive. 

Three more observations:
   1.  I'm told BMW's are set up the same way, but I kept hitting the cruise control lever instead of the turn signal.  It's very annoying to set the cruise control on HOLYSHITGO!!!! when you're accelerating and trying to merge into the next lane.
   2.  The car is fighting pretty hard to engage regenerative braking.  I know why it's doing it, and I applaud the efforts to eke out every mile possible (as well as to recharge the battery at a voltage that actually does something), but it takes some getting used to.  My Subaru was a stick (yes, I drove a stick for many years in and around DC), and the Tesla slows down as if the car was in 2nd gear the whole time.  This is adjustable, but of course, everyone wants the best mileage and range they can eke out.
   3.  My friend showed a picture of when he was charging at at Supercharger station when the battery was almost empty and "drinking" from the Supercharger as fast as it could: 226 amps at 371 volts.  226 amps at 371 volts is about 84 kilowatts.  That's about 14x more than your average house draws at full power.  Or, to put it another way, if you charge at 84 kilowatts for about 3 hours, that's roughly the same as your average house will drink in a week. 

I bring this up to compare to my previous calculation that about 20 megawatts of power (equivalent) is flowing through your gasoline hose when us ordinary folk fill up at the gas station.  So, there's a tremendous amount of electricity flowing through the wires, and some very talented engineers found a way to safely transfer all that power, but it's still two hundred times less power (equivalent) than is flowing through your gas hose at the gas pump.

[Nerd note on that last item: for any technically minded folks out there, I acknowledge that electric vehicles are about 3x more efficient that gasoline powered vehicles, thus making the "equivalent power" flowing only about a factor of 70 less than the gasoline pump.  But still.  70x.  Wow.  Gasoline is pretty energy dense.]

At this point, I would like to close with a picture of me in front of said Tesla but, alas, no pictures were taken.  You'll just have to take my word for it.

And thanks for the ride, Greg.

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