For Memorial Day weekend of 2013, we planned to take our family of four in a new Model S on a road trip from our home in Orange County to visit grandma's house in San Francisco's east bay. This would become our first long-distance road trip using an all-electric car. It did require a little bit of planning and preparation. First, I needed to figure out how much time we needed to spend at each Tesla Supercharger, and whether I needed all three (Tejon Ranch, Harris Ranch, and Gilroy) or just two.

Along the way, my curiosity led me to explicitly test the behavior of the Hawthorne Supercharger, starting with a depleted Model S battery and measuring its effect on it every five minutes. Then I fit a formula to that data so that I could describe that behavior mathematically.

That resulted in a Supercharger Table that became very useful for predicting how much recharge time we really needed, and also showed that a one-hour+ lunch stop in Harris Ranch was more than enough to make the last leg of the trip.

So here's a little picture log of this 946-mile trip in my Model S.

Cargo Space	The cargo space in the Model S is amazingly large and comparable in volume to that of the typical minivan. We did fill much of its space, but even so we easily had room for another suitcase and more.
Tejon Ranch Supercharger - Northbound	As we traveled, I logged the time, odometer, and range remaining for every event of interest. Time Event Range Remaining 1:04 pm Departed Home 255 3:28 pm Arrived Tejon 97 Range/Distance ratio: 1.18 Conditions: Hills and Heavy Traffic Being the beginning of Memorial Day weekend, traffic was against us, which definitely slowed us down and reduced our energy efficiency. Using the Supercharger at Tejon was quite simple. Plug it in, then don't worry about it. So we focused on the kids, getting frozen yogurt, then playing around for a while, then going to get drinks and snacks at Starbucks. Ours was one of four Tesla's charging there. It turns out all the extra prancing around by the kids and getting them fed and settled took over a half-hour longer than the charging time needed by the car, so we ended up with a nearly full battery, more than originally intended.
Harris Ranch Supercharger - Northbound	Time Event Range Remaining 4:32 pm Departed Tejon 260 6:14 pm Arrived Harris 117 Range/Distance ratio: 1.23 Conditions: Traffic Driving to Harris Ranch was simple enough. Again we could plug in and go into the restaurant. We called ahead for a reservation just in case it was too busy. We saw two other Tesla's charge. Like before, our kids were being antsy, refusing to choose what to eat, wanting time to play. The technology behaved exactly as predicted, but it was the kids again who had us wait an extra half hour. Time Event Range Remaining 7:17 pm Continued Charging 264 7:49 pm Departed Harris 271 10:25 pm Arrived SF east bay 39 Range/Distance ratio: 1.32 Conditions: Hills, Strong Winds, and Traffic This was the leg that was the greatest unknown to me, skipping the Gilroy Supercharger and proceeding with the final 173-mile leg of today's trip. From the sound of the wind it seemed we had 20-30 mph gusts pushing the car around. This region (the 580 highway east of Livermore) has wind farms, so this area is well known for such weather conditions. This extra air resistance increased our energy consumption, and knowing it was our longest leg, I reduced speed, which turned out to be unnecessary because we ended up with virtually the same range remaining as predicted.
Charging at Grandma's	Prior to the trip, I researched and determined that the dryer outlet plug was the standard 30 A three-prong type common across the US, but the location required a cable to snake 40 feet from the garage. So I purchased a 30-foot NEMA 14-50 6-gauge extension cord (the Tesla-supplied cable is 20 feet long) and the parts needed to build an adapter for a NEMA 14-50 plug to the dryer outlet plus a grounding wire to the plumbing. At home I assembled the adapter and tested out the whole system first. At grandma's house, I told the Model S to limit its consumption to 27 A, allowing a 10% safety margin. [Note: Tesla Motors Club members have pointed out that I should've limited it to 24 A. A 20% margin is considered necessary for continuous loads like charging EVs.] Charging worked perfectly at a speed of about 14 miles of range per hour.
Kids	My kids played with their cousins, and I gave them, as these kids' first ride in a Model S, a little thrill ride around town. They enjoyed it, yelling like on a roller coaster. When we stopped we all thought it was funny to let them hop and tumble in the trunk like it was a little playground. Yes, of course, we did not drive around like this...
Harris Ranch Supercharger - Southbound	Time Event Range Remaining 9:48 am Departed SFEB 266 12:22 pm Arrived Harris 63 Range/Distance ratio: 1.16 Conditions: Tailwind We casually took our time to leave grandma's house, but easily made it to Harris Ranch at lunchtime. This southbound leg felt like we had a tailwind and the wind noise was much less, and, given what I learned from the northbound leg, we had more than enough range remaining, so I increased speed of this leg. At the Harris Ranch, another Model S had a large dog on a doggie bed in the back trunk. Like before, however, one child couldn't choose what he wanted to eat, then after food arrived demanded the food he rejected the last time we were here. All told this added a half hour beyond the car's need for energy.
Tejon Ranch Supercharger - Southbound	Time Event Range Remaining 1:32 pm Continued Charge 263 2:10 pm Departed Harris 270 3:51 pm Arrived Tejon 134 Range/Distance ratio: 1.17 Conditions: Light traffic The drive to Tejon was quite pleasant. Upon arrival we took another opportunity to have frozen yogurt. Meanwhile a few other Tesla's arrived being admired by other travelers. Then the kids loved running around and playing, again extending our time by almost an extra hour. Time Event Range Remaining 5:05 pm Depart Tejon 265 7:08 pm Arrived Home 119 Range/Distance ratio: 1.13 Conditions: Traffic and Downhill The drive home was hampered by traffic, as expected for Memorial Day, but I knew we couldn't run out of range, so I pushed it.

In short, the technology worked exactly as we hoped. The experience of driving the Model S is so much more relaxing than a typical gas car because it does not have the extra engine and transmission noise, but especially because this car leaves behind the low-frequency rumble and roar that shakes one's innards. The Model S is an amazing road-trip car.

Like the trip north, going south it was the little humans aged 2 and 6 (throwing temper tantrums, taking extra naps, refusing to choose what to eat, running around, etc.) who extended our stay at each stop, well beyond the car's need for charge.

Consumption going south was considerably less than each segment going north. It's as if we had a tailwind pushing us south. Actually the SF to Harris segment was definitely less windy, from the sound in the car, than going north.

The range consumed and average speed for each segment:

Northbound			Southbound
Leg	Range Consumed	Average Speed	Leg	Range Consumed	Average Speed
OC - Tejon	158 miles	56 mph	Tejon - OC	146 miles	64 mph
Tejon - Harris	143 miles	68 mph	Harris - Tejon	136 miles	69 mph
Harris - SFEB	232 miles	67 mph	SFEB - Harris	203 miles	73 mph

Note our average southbound speed, for each driving segment, was higher than our northbound speed. The data from the trip north told me we had enough margin to drive faster, which I applied to the trip south.

Translating this into energy, the conversion would be 85 kWh / 270 mi of range = 315 Wh/mi. At 12 cents per kWh, that means the cost of "fuel" was $20.41 to go north and $18.33 to drive south. Cut that down by a third if the Tesla Superchargers' energy are considered "free". Fueling my previous (gas) car on such a trip would easily be five times the price.

To think a year earlier no production electric car could make either family trip in a day.* (Or maybe not at all?) I think that's an accomplishment.

After this trip, I've also taken this Model S on several trips each using only one charge.

Dean E. Dauger holds a Ph. D. in physics from UCLA, where his group created the first Mac cluster in 1998. Dr. Dauger is the award-winning author in multiple American Institute of Physics' Software Contests and co-authored the original, award-winning Kai's Power Tools image-processing package for Adobe Photoshop. After founding his company, Dauger Research, Inc., its debut product, Pooch, derived from Dr. Dauger's experience using clusters for his physics research, was soon awarded as "most innovative" by IEEE Cluster and continues to revolutionize parallel computing and clusters worldwide with its patented technology.

*While the Tesla Roadster was known to make this trek, it can't carry my family and ended production in January 2012. Non-Tesla production electric cars can't make the distance between charging stations available then, or don't have the capacity, or couldn't charge fast enough to finish in a day.