The EV Experience

Stephen Casner, Fellow, Packet Design, March 28, 2007

Stephen Casner spent 25 years working on protocols and systems for transmission of audio and video over packet networks, starting before the Internet existed and continuing through the Internet Multicast Backbone (MBONE). He was recruited to the Silicon Valley to work with startup Precept Software and its IP/TV product, which was later acquired by Cisco. He is currently a Fellow at Packet Design, working on route analytics, and waiting patiently for his Signature One Hundred number to be called.

I’ve been driving production electric vehicles since November, 1998, when I took delivery of a General Motors EV1. I lost that first-generation EV1 when it was recalled in March 2000, but two months later I was able to lease a Gen 2 EV1 with NiMH batteries. GM pried that one out of my fingers when the three-year lease was up. I managed to continue driving electric by leasing a Ford Ranger EV pickup, but again that was only for a year before it was taken back. Luckily, I was given the opportunity to lease or buy one of the last few 2003 Toyota RAV4-EVs. Given the EV1 lease experience, the choice to purchase was obvious!

Electric Drive
I have to admit that I was a bit uncertain when I first went to see the EV1, but the technology appealed to me. My wife was skeptical, but willing to let me have the car for my use while she kept the trusty Honda. However, neither of us knew how much more pleasant and fun to drive the EV1 would be. It was not long before the EV1 became the favored car. Now that we have the RAV4-EV, guess who stakes claim to that one? I’m back to buying gasoline again, and can’t wait to get our Tesla Roadster.

It turns out that electric propulsion is just superior to an internal combustion engine in many ways. Most people don’t realize this. I’m not talking about the technical advantages such as having fewer moving parts, not needing a reverse gear, and minimizing brake wear. I’m referring to the nicer "pedal feel." This may be hard to describe – you must get behind the wheel to experience it.

I've always hated automatic transmissions because of the way they lurch when starting from a stop and because of the minimal engine braking they provide when I want to decelerate. The coupling between the right foot and the road is just too slushy. I submit that people who prefer a manual transmission don't do so because they enjoy the exercise of shifting and clutching in stop-and-go traffic. Rather, it is the greater degree of control over the engine's operating point provided by selecting a gear and adjusting the accelerator.

With a good electric drive, you get the best of both worlds: easy driving with little or no shifting, as well as very precise control of speed, both accelerating and decelerating. The EV1 was excellent in this regard – it was easy to maintain a constant speed floating along at cruising power level, with a smooth and responsive transition either to increase or reduce speed. The RAV4-EV is not as good. The onset of regenerative braking is too sharp. I have high expectations for the Tesla Roadster to be even better than the EV1, with smooth transitions and a wide-enough "flat spot."

Stephen, his wife, and the RAV4

I’m also hoping that the amount of regenerative braking force in the Tesla Roadster is high enough to provide sufficient deceleration when desired. Tesla Motors suggests that you can drive in second gear all the time, since that will cover the whole speed range. However, since this car will be my daily driver on a non-freeway commute, I anticipate driving much of the time in first gear to select its higher regen level. With the Ranger-EV, I shifted out of the similar "econ" mode only a few times in the year that I had it. This allowed me to drive the twisty highway over the mountain from Santa Cruz to home without touching the brakes.

You've all heard that the Tesla Roadster will go from 0 to 60 mph in about four seconds, and that is great for jumping into the carpool lane on Northern California freeways. The EV1 was good at that, too, but it was not a feature I needed all that often. On the other hand, one of the things I liked most about the EV1 was the availability of full torque at low speeds, such as to smoothly pull over the bump getting into my garage every day without having to gun the engine and risk driving into the back wall. (And it did this silently to boot, great for sneaking in late at night!)

Last but certainly not least is the convenience of never going to a gas station. We didn’t buy any gas from Christmas until August during the time when we had both the Ranger-EV and RAV4-EV. Try home refueling for a while and you’ll never want to give it up. Plus, if you invest in a solar photovoltaic system, as we have done, the refueling can be pollution- and carbon-free. Toyota's Prius advertisements that claim "you never have to plug it in" are 180 degrees off the mark.

Energy Management
At first, I had some concern about the limited range of the first generation EV1 with lead-acid batteries – about 60 miles in the summer and 40 miles in the winter, when the cold temperatures reduced battery performance. However, since my commute was only 25 miles round trip and I could charge every night at home, I quickly learned that the limited range was not really a problem for my intended use.

Clearly, this required a different mind-set. The full range of the Gen 1 EV1 was about the same as the number of miles remaining when the low-fuel warning indicator comes on in many gas cars. It took a little time to become comfortable with energy management before we ventured further with the EV1. But we did drive that car 128 miles from home in Silicon Valley to Sacramento with two recharge stops in between. (Vacaville has lots of public chargers and a cinema nearby.) That was mostly for the adventure, and to attend a hearing of the California Air Resources Board about the ZEV Mandate. Of course, our trip was nothing compared to Kris Trexler’s "Charge Across America" trip from Los Angeles to Detroit.

Stephen and an EV1 Club tackle the
Scenic 49-Mile Drive in San Francisco

With a bit of experience we knew what to expect from the car and how much energy would be required to reach a particular destination. Our key to gaining that knowledge was a program for the Palm Pilot called EV1Dash, which connected to the car’s OBD-II diagnostic connector and read out more precisely the battery percent state of charge and other parameters. It also estimated range with three different averaging intervals and indicated how efficiently one was driving. The EV1Dash program allowed continuous recording of odometer, speed, voltage, and current. This data could then be downloaded and graphed to see the energy profile for a particular trip. This has terrific geek value!As a person interested in physics, I enjoyed taking an occasional peek at the instantaneous power level displayed on the Palm. You would be surprised how much the power varies going up, over, and down a freeway overpass. The car was a rolling demonstration of the principle of Conservation of Energy.

An important lesson we learned for minimizing energy use and maximizing range is to use cruise control whenever possible. This not only avoids going faster than intended (which takes more power for the increased drag), it also avoids the small, unnecessary accelerations and decelerations that consume more energy. This experience changed my driving style such that I now use cruise control almost all the time, even in my gas car. Consequently, I consider a well-performing cruise control to be a key feature of the Tesla Roadster, too.

When we graduated to the Gen 2 EV1 and the RAV4-EV with 100 miles range, we paid less attention to energy management except when we would drive 92 miles to EV1 Club meetings in Vacaville. There were a few times when we drove back into the garage at home with zero percent showing on the Palm, but we’ve never needed a tow.

The greater range of the Tesla Roadster means even less concern about battery charge level. In fact, I’m quite pleased that Tesla Motors plans to give drivers control to limit charging to 50 percent or 90 percent, as needed, in order to maximize battery life—something GM and Toyota would not consider. However, I still expect I will be tempted to occasionally drive to the limits of the Tesla Roadster’s range, so I want plenty of details available from the Vehicle Display System (VDS). This should be feasible since it is integrated with the vehicle rather than being a driver add-on, right Tesla?

Looking Forward to the Tesla Roadster
It was a fairly easy decision for me and my wife to buy the Tesla Roadster, even though we've never paid even half as much for a car before. Driving electric is important to us. I have confidence in Tesla Motors because the founders were my co-workers (at Packet Design) before they left to start Tesla Motors. I had several conversations about EVs with Martin in those days, and I've had the opportunity to visit Tesla Motors a number of times and watch it grow from three people to the present size. I've seen first-hand the level of detail that has gone into the design and development of the Tesla Roadster.

What impresses me is the large number of Tesla Motors customers who have put down a deposit without even seeing the car in person. These are people who have enough money and vision to make a commitment. As I said earlier, other people may assume they'll have to accept some compromise in the driving experience in order to "go green," but they are mistaken. If you'll forgive me for repeating a car salesman's cliché, I'm convinced that all we have to do is get people into this car and its successors, and they will understand. They, too, will have a chance to experience "the EV1 smile" we've seen so often.