First Houston - Austin day trip: 300+ all EV miles

First Houston - Austin day trip: 300+ all EV miles

For the first time since buying my Tesla Model S 85D in April, I decided to take a zero emissions road trip! Now normally this is no big deal in a car with an 85 kW battery and an EPA rated range of 270 miles. Tesla has built a great network of Superchargers that are designed to make road trips about as worry-free as with an ICE vehicle. But if you are making a day-trip, the challenge is a bit greater.

My goal was to use only the Tesla superchargers because my office in Austin does not offer any charging options and I didn't want to prolong my trip with an unnecessary stop in Austin at 5pm on a Friday. I needed to make the 300+ mile journey only using the Columbus, TX supercharger site.

Since the roundtrip distance between the supercharger and my office in Austin is 203.5 miles, I thought it was very doable with an EPA rated range of 270 (which assumes using about 300 Wh of energy for every mile driven). But I needed to take into consideration speed, HVAC usage, tire variations, weight, etc. All these factors could easily push my average energy usage to 400 Wh, which at 203.5 miles would put me in a real danger zone to make the trip.

This is where the excellent web site evtripplanner.com came in. Using the site I was able to select my exact car configuration, including tires, speed and cargo weight to determine how much energy I would need for my trip. In the screen shot below you can see that assuming I am within 5% of the average speed of other drivers, I can make the roundtrip distance using 68.5 kWh or 228 rated miles, for an average energy efficiency of 337 Wh/mile. This is excellent information to have in order to make sure you drive correctly throughout your journey to ensure you have enough energy.

Trip plan from Columbus, TX to Austin, TX roundtrip

Battery level at Columbus supercharger

I live in Katy, TX about 53 miles from the supercharger and decided to charge to 90% (appx. 240 rated miles) overnight at home as there was no need to complete a full range charge. When I reached the supercharger I had 178 rated miles left "in the tank". I started charging and decided to go to the McDonalds nearby for a restroom break and a little breakfast. Thanks to evtripplanner.com I knew I needed at least 228 rated miles before leaving the supercharger (but one should always have a buffer of 10-20% extra, so I really wanted to get to at least 240 rated miles). Charging took approximately 30 minutes to get me to about 95% of charge or about 258 rated miles.

Trip meter upon reaching Austin

I made it to Austin with a minute to spare before my 9:30 meeting, driving pretty much the same as all other drivers. I averaged 317 Wh/mile, using 32.5 kWh of energy for 102.4 miles. My battery showed 145 rated miles remaining for the trip back to Columbus. Sounds perfect! Perfect except for:

  • Vampire battery drain during the work day
  • Notorious Austin Friday afternoon traffic
  • The incredible heat of an Austin summer

Interior car temp of 136 degrees fahrenheit when leaving Austin

I lost about 1% of battery range, or around 2.5 miles during the day - no big deal, but it is something to consider when you are managing closely like I was. There was nothing I could do about the Austin traffic except to monitor my energy consumption and potentially consume less on the highway back (which I did, more on this below). I did put the car in Range mode in order to conserve more energy, especially with the HVAC system. Using the wonderful Remote S iPhone app,  I checked the temperature of the car before leaving the office at 5pm.

I decided to use Tesla's Beta trip planner software built into the Nav unit on the way home. I programmed the destination of the Columbus supercharger, but it insisted on routing me through San Marcos first, a detour adding 30 miles and about 45 minutes of additional drive time. In order to get what I wanted from the car's navigation, I tapped the "Trip" button, then tapped "Remove all superchargers". At this point the car told me I can reach Columbus with about 9% of battery range remaining. Due to higher than anticipated energy use in Austin stop and go traffic, I received the warning one or twice that I needed to slow down to reach my destination. I went 65-70 miles per hour (an avg of 5 mph slower than my drive over) for a while, until the Trip panel of the car showed that I would reach with 11% remaining. When I grew confident in my energy use and the monitoring of the trip info, I resumed driving at the speed limit of 75 mph.

Battery levels on return to supercharger

I reached the supercharger again with 27 rated miles of range remaining, or about 10%. I had consumed an average of 311 Wh/m or 63.5 kWh of energy during the 204.8 mile journey. I put in my home destination some 53 miles away and the car told me I should supercharge for 10 minutes. I went to the restroom and stretched my legs, charging for 15 minutes then I was on my way home.

All in all, driving all EV added about 45 minutes to my drive (30 minutes charging at first stop, 15 minutes at the second). Given that I would have stopped in my ICE car for a bit at some point, it is more like 30 minutes extra time added.

Here are my takeaways from the trip, which I will do again soon:

  • Evtripplanner.com is awesome! Please use it and donate to the creators. It takes the guesswork out of EV driving.
  • The Model S is a dream to drive on a road trip, especially with the autopilot traffic aware cruise control (TACC).
  • Be sure and use range mode to get the maximum miles from your battery.
  • The Columbus, TX supercharger is well maintained but a bit out of site from the road. Look behind the Comfort Suites.
  • The Trip planner app in the car is quite useful, once you force it to take your itinerary.

I hope this helps someone else plan their first day trip. Please send me questions in the comments or tweet me @RAndersonTexas.