Electric VehiclesMay 17, 2009

Discover how a Porsche 356 reproduction turned electric defies expectations with its innovative design and powerful performance. Learn about its transformation, battery tech, and the electric driving experience.

The Porsche 356 was one of the most beloved sports cars ever built. There were 1,171 of them originally created and some 20,000 reproductions manufactured in the years since. We think this one may be a little better.

This is actually one of the reproductions. It was created as a glider by Special Editions Inc. of Bremen, Indiana.

It has a fiberglass body and a 3-inch tubular chassis that's stiffer and stronger than the original pan Porsche used. We selected it as our first project for an electric car.

Most people's understanding of the concept of an electric car is intimately involved with their understanding of golf carts. I know mine was. And I originally expected a full-size automobile converted to electric to drive a little bit like a golf cart. As it turns out, it doesn't.

In this segment, we're going to show you a little bit about what it feels like to drive in an electric car. This was our first electric car project and a simple one. It's turned out to be sufficiently successful, both in handling and feel and in acceleration, that we're going to go on it to some more advanced projects.

We'll also show you a little bit about what Special Editions calls the Beck 356 Speedster and our conversion to totally electric power. I'm Jack Rickard.

Inside the engine compartment, the first thing you'll notice is the Net Gain Warp 9 motor, which we've coupled to the Pro Street Racer VW transaxle with this bellhousing adapter.

We've used a taper lock coupler to make the shaft to the flywheel, which we lightened to nine pounds, retaining the clutch and all four speeds of the existing manual transmission and the rest of the drivetrain. The Net Gain motor is a series wound DC motor. We're operating at a nominal voltage of 105 volts.

It's rated at 72 volts, 330 amps for 32 horsepower continuous operation. Electric motors are rated on a one-hour continuous operation basis, and it's basically a function of their ability to dissipate heat. Gasoline engines, like the CB Performance 180 horsepower engine we removed, are rated in horsepower at their peak horsepower.

So there's a big difference between talking electric motor horsepower and gasoline engine horsepower. This motor, we can easily operate at five or six times its rated horsepower for the brief periods that you encounter and stop and go driving under acceleration. With our Kelly controller, which will apply up to 1200 amps at 105 volts, we can achieve a peak of 160 horsepower with this motor.

And better, it'll apply that horsepower across the entire RPM band of zero to 5,500. On either side of the motor, we have our ThunderSky lithium-ion batteries. These are a new kind of battery that I think make electric cars viable in a way that the lead acid simply didn't.

We've arranged these four cells to the battery, eight batteries in a bank, one bank in the front of the car, one bank in the back, and that's allowed us to achieve a 50-50 weight distribution. The total weight of the batteries is 489 pounds. If we did 16 Trojan lead acid batteries, that'd be about 1,350 pounds.

So you can see that the lithium-ions provide us greater power at less weight, making the car really viable. The Kelly controller is what applies that pack voltage to the motor. The motor's speed is a function of voltage, and there's the Kelly there.

The torque of the motor is a function of its current, and if we applied the full battery pack to it, we would immediately go full speed. We use the accelerator input to modulate a 16 kilohertz waveform pulse width modulation to provide an average voltage and current to the motor, and this is a fairly efficient conversion, about 95 percent, and gives us complete control of the motor from a very low-speed crawl up and very smooth acceleration up to 85 miles an hour. We could get a different top speed by a different battery configuration with a higher voltage, but 85 is about as fast as I care to go in a light convertible.

In the upper right-hand corner, we have two 1500-watt heating elements, and we apply the pack voltage to that through a switch on the dash, and a blower that blows air through it up into the passenger compartment. We've got a blower system for the motor to provide additional cooling. It's proven to be largely unnecessary, but it should extend the life of the motor somewhat.

So on the right-hand side, you see a DC distribution block, simply some fuses, to distribute power to our taillights and headlights and so forth. We have a 12-volt DC-to-DC converter that takes pack voltage and makes 12 volts for our normal automobile operations. In the front of the car, there's not much to see here, frankly.

Of course, the original Beck 356 Speedster, like most of the Porsches and Volkswagens, the front's where you kept the spare tire, gasoline tank, and so forth. We've got most of this covered up. Underneath this particular panel, we do have some more batteries.

This is our charging socket here, a disconnect switch here, more batteries under here where the spare used to go. These are some terminal strips we use for testing and monitoring. They actually don't have anything to do with the operation of the car.

And putting batteries front and back, again, we've got that equal distribution of weight between the front and the back of the car. The cockpit of the car is appointed, typical Porsche fashion. One of the key functions we did add was in the instrument cluster, the speedometer works as normal.

The tachometer does as well, but in the center of the cluster, you'll see an eVision instrumentation system. This allows us to monitor pack voltage, current used, kilowatt hours used, amp hours, any of the various data that we might need to see while operating the car as an electronic device. Let's talk a little bit today about living with an electric car.

First, most Americans haven't actually experienced an electric car other than a golf cart on a golf course, and an electric car is quite different. Life with an electric car is pretty good. For one thing, I don't go to the gas station very much, and I found it enormously convenient to charge the car at home and some surprises in living with it.

Third, this car, our first conversion uses some new batteries called ThunderSky lithium iron phosphate cells that make it quite different from living with most of the electric cars that are out there. The two questions that most people immediately seize on are, of course, how far can I drive the car, what's the range, and how long does it take to recharge the car? Those questions, of course, are both valid. What you'll find in living with the electric car is they're not nearly as important as you thought they were, but since they're often asked, let's talk about the answer.

This particular car weighs 2,130 pounds. It uses about 235 watt-hours per mile or 1.9 amp-hours per mile, and that gives it a range of about 75 miles.