ITI JAIL ROAD | ELECTRIC VEHICLE TEST

The accelerator pedal hooks to a pair of potentiometers (variable resistors), and these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.

There are two potentiometers for safety’s sake. The controller reads both potentiometers and makes sure that their signals are equal. If they’re not, then the controller doesn’t operate. This arrangement guards against a situation where a potentiometer fails in the full-on position.

The controller creates three pseudo-sine waves. It does this by taking the DC voltage from the batteries and pulsing it on and off. In an AC controller, there is the additional need to reverse the polarity of the voltage 60 times a second. Therefore, you actually need six sets of transistors in an AC controller, while you need only one set in a DC controller. In the AC controller, for each phase you need one set of transistors to pulse the voltage and another set to reverse the polarity. You replicate that three times for the three phases — six total sets of transistors.

Electric cars can use AC or DC motors. If the motor is a DC motor, then it may run on anything from 96 to 192 volts. Many of the DC motors used in electric cars come from the electric forklift industry. If it is an AC motor, then it probably is a three-phase AC motor running at 240 volts AC with a 300 volt battery pack.

Running any electrical accessory reduces fuel economy, having the air conditioner on the maximum setting can cut efficiency 5 to 25 percent, according to the U.S. Department of Energy.

When the U.S. Congress passed legislation requiring automakers to achieve increasingly stringent goals for fuel economy figured by the average of each manufacturer’s sales-weighted fleet, the U.S. average for total passenger vehicles was 15.9 miles per gallon.

Only about 14-26 percent of the energy from the fuel you put in your tank gets used to move your car down the road, depending on the drive cycle. The rest of the energy is lost to engine is lost to engine inefficiencies, or is used to power accessories.

In the 1830s, Robert Anderson of Scotland, Vermont blacksmith Thomas Davenport, and Dutch Sibrandus Stratingh built carriages, carts, and motors that are seen as forerunners to the electric car.

French engineer and mechanic Nicolas-Joseph Cugnot in 1769 designed the first “horseless” carriage, used by the French Army artillery , which ran on a stram engine. It was so heavy that it could move no faster than 2.5 miles (4 kilometers) per hour.

The Battery. Most of the other stuff is pretty much the same as any car, but batteries are big, heavy and expensive.