Freedom Trail

I have occasional business in Our Nation's Capitol speaking truth to power.  Usually, I fly up there on an airplane.  It's a nonstop to DCA on Delta or US Airways.  No biggie.  4 hours door to door.  This time, I decided to take my magical space car.

On my previous road trip, I stopped for a day in DC on my way out to Las Vegas, so I know it's not an unpleasant journey.   So, I made the command decision to make my next trip in my Tesla Model S.

Time Series

Our company's product, Epinomy, is all about time series.   So, I thought it would be interesting to track the telematics the Model S provides as input to Epinomy.   Of course, Epinomy is really made for storing millions of data points from thousands of data sources, so my one measly trip will not generate enough data to be *really* interesting.  For that, I'd need to gather the telematics of multiple cars over long periods of time.  Maybe someday, but for my little science experiment, this will have to do.

Model S iPhone Application

Model S iPhone Application

Capturing telematics from a running Tesla is not that difficult.  For all of the news about "hacking" into the car, the API itself is quite easy to use.  It is an ordinary RESTful API.  Of course, the catch is you need to be a Tesla owner and provide the proper login credentials to access your car.  Every Model S owner is given a login to the My Tesla web site, which allows access to information about their car, including telematics.  This is how the mobile app accesses your car as well.

My friend Joe Pasqua wrote an open source Java application called "Visible Tesla".  It is an outstanding piece of engineering, especially for a hobby.   

Visible Tesla uses the same techniques as the mobile app developed by Tesla.  It provides the same features, plus a whole lot more.  Some of the things that Visible Tesla does that you cannot do on the mobile app include;

  • Tracking and storing all telematics available from the car.
  • Tracking and storing trips by map coordinates.
  • Full scheduled operations.  For example, "turn on the climate control at 8:00 AM".
  • Event notification.  For example, "send me a text when charging is complete".
  • And many more.  

Teslarati has a really good article on Visible Tesla and tells you how to get it and install it.

Visible Tesla Overview Page

Visible Tesla Overview Page

In order to be useful for my journey, I needed to keep the Visible Tesla app running on my desktop so that it could continually poll my car for updates.   This is not a big deal, and there are good reasons why the author designed it that way.  I installed and ran the app on my desktop, and kept it running for the entire trip.

I'm kind of a grizzled veteran of Tesla road trips.   My first one was a doozy, across the frozen tundra on a brand new supercharger network and all-season tires.   This trip is a comparative piece of cake.

So, I packed up my business suit (they wear suits in DC, even in summer time), put it in the trunk and headed on my way Sunday morning.  Theoretically you can drive non-stop to DC from Tampa.   But it will be grueling, and possibly dangerous.   Last time, I got a late start and only made it as far as Lumberton, NC.   This time, I got a bit of an earlier start (although not the 7:30 AM start that I was shooting for).

Tampa to DC roundtrip annotated graph

The Visible Tesla tracks all of the indicators available from the car over the API, including:

  • Voltage
  • Current
  • Range
  • State of Charge
  • Rate of Charge
  • Power
  • Speed
  • Battery Current

On the attached annotated screen grab, you can see all kinds of interesting characteristics of the journey.   I've kept some of the redundant values off the chart to concentrate of some of the more interesting observations.  It is kind of cool how the range of 0.0 to 400 is a suitable range for many of the values, so the Y-axis of the chart is all of the same order of magnitude even if it is tracking disparate units of measure such as miles, volts, amperes, percent and velocity.  They all fit nicely in a single line chart.

Range, in miles, is the red chart line.   Toward the left of the chart was Saturday, the day before my trip, where I only drove about 30 miles, about typical.  You can see the blip where I topped it off the night before I left.

I set the "range charge" mode to 100%, or 264 miles of rated range.  This is only recommended for special occasions. One of the properties of the lithium ion batteries in the Tesla is that there is a "sweet spot" of charge between 20% and 80% of capacity.  To maximize battery life, you should not regularly charge above 80% or 233 miles range on an 85 kWh battery. But for the occasional road trip, it's okay.

On my first trip earlier this year, I did charge the batteries to full range on a couple of occasions because it was freakin'' cold and the Tesla uses battery power to heat the cabin.  Remember, there's no inefficient waste heat from an electric motor like there is in an internal combustion engine.  The distance between chargers averages about 120 miles, but Tampa to Port Orange and Saint Augustine to Savannah are over 150 miles.  You really need 80% charge to have a good comfortable slack.  I didn't come close to running out of charge at all on this trip.  Mostly because I now know how to use the "Projected Range" feature properly.  

Day One - Sunday

The first segment of the trip is one of the longest.  It goes from Tampa Bay area on the west coast of Florida, though Orlando an across the state to Port Orange.   This is about 160 miles.  I can easily make that with a "daily" charge of 233 miles, but I topped it off to be safe.   

As I start on my journey, you can see the red "range" value goes down steadily as I drive.  The green line hovers up around 70-75 mph.   I arrived at Port Orange with about 75 miles of rated range on the battery.  

It is only 65 miles between Port Orange and Saint Augustine, so there was a greater than zero chance that I could make it without stopping if I went just a bit slower and drove a bit more conservatively.   But what's fun about that?  

You notice that I only charged to about 175 miles of range in Port Orange, because that's plenty to get me to Saint Augustine.  That charge only took me about 15 minutes.

In the Saint Augustine outlet mall, I needed much more of a charge.   It is 155 miles to Savannah - the second longest segment of the journey.  I spent about 35 minutes there, mostly because I was having a nice conversation with a father and his daughter who had driven all night from Ohio.  

I pulled into Savannah with less than 50 miles of rated range remaining.   Still plenty of cushion, so I set the charger to stop at 80%, the same as I do for daily commuting.  Because the battery was pretty low, the Supercharger was able to pump a lot of electrons in very fast.   Notice how the charge rage is 360 miles per hour when I first plug it in.   

Charging a Li-ion battery is like filling a bucket of water without overflowing the edges.  When the bucket (battery) is empty, you can put water (electrons) into it much faster without worrying about overflowing.  "overflowing" is very bad and can destroy a battery, so Tesla has a charging algorithm that slows down the charge as it fills up.  This is why they say you can get "half a charge in 20 minutes".   That's true if the battery is empty.  However, when it is full, that last 50% takes another hour or so to finish.  Fortunately, you don't usually need a full battery to make it to the next charger, so 20-30 minutes charing is very realistic on a long trip.

You can see the trips to Santee, Lumberton and Rocky Mount are pretty similar.  All of those Superchargers are about 115-120 miles apart.  

In Santee, I got deluged with rain and had to find an alternate way out of the parking lot.   I don't want to find out if my Model S can float.

Day Two - Monday

Monday, I had an afternoon meeting in Tyson's corner.   I *thought* I had plenty of time to leave at a leisurely 9:00 AM, get to Glen Allen outside of Richmond by my 11:00 conference call, have a leisurely lunch and then make the trip up to DC area.  

I had lunch at Chipotle, which is thoughtfully placed across the street from he Supercharger. When I got back to my car a young guy and his girlfriend chatted me up about the car.  It was the usual stuff.  I offered to give them a ride and they accepted.  We did the usual 0-60 in the parking lot kind of grin-inducing revelry.   I told them to work hard and maybe they could be as cool as me and have an electric car.

I got out of there at around 1:00, and the GPS told me I'd be about an hour early for my meeting. I started planning what I was going to do with all that extra time waiting around for my appointment time.  That was before I encountered the SNAFU that is Richmond-to-DC-on-I95 traffic.  I actually remembered this from the last time I came through 5 months earlier.   But I that that was because of an accident.   Nope.  The only accident was believing that it was an accident.

I was 30 minute late for a meeting that I should have been an hour earlier for.

I used to find a five-star hotel for $150 in Washington effing DC, bitches!  

Of course, they got north of $50 just to park the thing.  It's like there is no outside world where people know how much things cost.

Next post:  Tesla Grins, Tesla Giggles and the drive home.