Electric Automobile (How Products are Made)
Unlike the gas-powered automobile, the electric automobile did not easily develop into a viable means of transportation. In the early twentieth century, the electric car was vigorously pursued by researchers; however the easily mass-produced gasoline-powered automobile squelched interest in the project. Research waned from 1920-1960 until environmental issues of pollution and diminishing natural resources reawakened the need of a more environmentally friendly means of transportation. Technologies that support a reliable battery and the weight of the needed number of batteries elevated the price of making an electric vehicle. On the plus side, automotive electronics have become so sophisticated and small that they are ideal for electric vehicle applications.
The early development of the automobile focused on electric power rather than gasoline power. In 1837, Robert Davidson of Scotland appears to have been the builder of the first electric car, but it wasn't until the 1890s that electric cars were manufactured and sold in Europe and America. During the late 1890s, United States roads were populated by more electric automobiles than those with internal combustion engines.
One of the most successful builders of electric cars in the United States was William Morrison of Des Moines, Iowa, who began marketing his product in 1890. Other pioneers included S. R. and Edwin Bailey, a father-son team of carriage makers in Amesbury, Massachusetts, who fitted an electric motor and battery to one of their carriages in 1898. The combination was too heavy for the carriage to pull, but the Baileys persisted until 1908 when they produced a practical model that could travel about 50 mi (80 km) before the battery needed recharging.
Much of the story of the electric car is really the story of the development of the battery. The lead-acid battery was invented by H. Tudor in 1890, and Thomas Alva Edison developed the nickel-iron battery in 1910. Edison's version increased the production of electric cars and trucks, and the inventor himself was interested in the future of the electric car. He combined efforts with the Baileys when they fitted one of his new storage batteries to one of their vehicles, and they promoted it in a series of public demonstrations. The Bailey Company continued to produce electric cars until 1915, and it was among over 100 electric automobile companies that thrived early in the century in the United States alone. The Detroit Electric Vehicle Manufacturing Company was the last to survive, and it ceased operation in 1941.
Electric automobiles were popular because they were clean, quiet, and easy to operate; however, two developments improved the gasoline-powered vehicle so much so that competition was nonexistent. In 1912, Charles Kettering invented the electric starter that eliminated the need for a hand crank. At the same time, Henry Ford developed an assembly line process to manufacture his Model T car. The assembly was efficient and less costly than the manufacture of the electric vehicle. Thus, the price for a gas-driven vehicle decreased enough to make it feasible for every family to afford an automobile. Only electric trolleys, delivery vehicles that made frequent stops, and a few other electric-powered vehicles survived past the 1920s.
In the 1960s, interest in the electric car rose again due to the escalating cost and diminishing supply of oil and concern about pollution generated by internal combustion engines. The resurgence of the electric car in the last part of the twentieth century has, however, been fraught with technical problems, serious questions regarding cost and performance, and waxing and waning public interest. Believers advocate electric cars for low electrical energy consumption and cost, low maintenance requirements and costs, reliability, minimal emission of pollutants (and consequent benefit to the environment), ease of operation, and low noise output.
Some of the revived interest has been driven by regulations. California's legislature mandated that 2% of the new cars sold in the state be powered by zero-emissions engines by 1998. This requirement increases to 4% by 2003. Manufacturers invested in electric cars on the assumption that public interest would follow the regulation and support protection of air quality and the environment. General Motors (GM) introduced the Impact in January 1990. Impact had a top speed of 110 mph (176 kph) and could travel for 120 mi (193 km) at 55 mph (88 kph) before a recharging stop. Impact was experimental, but, later in 1990, GM began transforming the test car into a production model. Batteries were the weakness of this electric car because they needed to be replaced every two years, doubling the vehicle's cost compared to the operating expenses of a gasoline-powered model. Recharging stations are not widely available, and these complications of inconvenience and cost have deterred potential buyers. In 1999, Honda announced that it would discontinue production of its electric car, which was introduced to the market in May 1997, citing lack of public support due to these same deterrents.
Unlike primary batteries that have a limited lifetime of chemical reactions that produce energy, the secondary-type batteries found in electric vehicles are rechargeable storage cells. Batteries are situated in T-formation down the middle of the car with the top of the "T" at the rear to provide better weight distribution and safety. Batteries for electric cars have been made using nickel-iron, nickel-zinc, zinc-chloride, and lead-acid.
Weight of the electric car has also been a recurring design difficulty. In electric cars, the battery and electric propulsion system are typically 40% of the weight of the car, whereas in an internal combustion-driven car, the engine, coolant system, and other specific powering devices only amount to 25% of the weight of the car.
Other technologies in development may provide alternatives that are more acceptable to the public and low (if not zero) emissions. Use of the fuel cell in a hybrid automobile is the most promising development on the horizon, as of 1999. The hybrid automobile has two power plants, one electric and one internal combustion engine. They operate only under the most efficient conditions for each, with electric power for stop-and-start driving at low speeds and gasoline propulsion for highway speeds and distances. The electric motor conserves gasoline and reduces pollution, and the gas-powered portion makes inconvenient recharging stops less frequent.
Fuel cells have a chemical source of hydrogen that provides electrons for generating electricity. Ethanol, methanol, and gasoline are these chemical sources; if gasoline is used, fuel cells consume if more efficiently than the internal combustion engine. Fuel cell prototypes have been successfully tested, and the Japanese began manufacturing a hybrid vehicle in 1998. Another future hope for electric automobiles is the lithium-ion battery that has an energy density three times greater than that of a lead-acid battery. Three times the storage should lead to three times the range, but cost of production is still too high. Lithium batteries are now proving to be the most promising, but limited supplies of raw materials to make all of these varieties of batteries will hinder the likelihood that all vehicles can be converted to electrical power.
The electric car's skeleton is called a space frame and is made of aluminum to be both strong and lightweight. The wheels are also made of aluminum instead of steel, again as a weight-saving method. The aluminum parts are poured at a foundry using specially designed molds unique to the manufacturer. Seat frames and the heart of the steering wheel are made of magnesium, a lightweight metal. The body is made of an impact-resistant composite plastic that is recyclable.
Electric car batteries consist of plastic housings that contains metal anodes and cathodes and fluid called electrolyte. Currently, lead-acid batteries are still used most commonly, although other combinations of fluid and metals are available with nickel metal hydride (NiMH) batteries the next most likely power source on the electric car horizon. Electric car batteries hold their fluid in absorbent pads that won't leak if ruptured or punctured during an accident. The batteries are made by specialty suppliers. An electric car like the General Motors EV1 contains 26 batteries in a T-shaped unit.
The motor or traction system has metal and plastic parts that do not need lubricants. It also includes sophisticated electronics that regulate energy flow from the batteries and control its conversion to driving power. Electronics are also key components for the control panel housed in the console; the on-board computer system operates doors, windows, a tire-pressure monitoring system, air conditioning, starting the car, the CD player, and other facilities common to all cars.
Plastics, foam padding, vinyl, and fabrics form the dashboard cover, door liners, and seats. The tires are rubber, but, unlike standard tires, these are designed to inflate to higher pressures so the car rolls with less resistance to conserve energy. The electric car tires also contain sealant to seal any leaks automatically, also for electrical energy conservation. Self-sealing tires also eliminate the need for a spare tire, another weight- and material-saving feature.
The windshield is solar glass that keeps the interior from overheating in the sun and frost from forming in winter. Materials that provide thermal conservation reduce the energy drain that heating and air conditioning impose on the batteries.
Today's electric cars are described as "modern era production electric vehicles" to distinguish them from the series of false starts in trying to design an electric car based on existing production models of gasoline-powered cars and from "kit" cars or privately engineered electric cars that may be fun and functional but not production-worthy. From the 1960s-1980s, interest in the electric car was profound, but development was slow. The design roadblock of the high-energy demand from batteries could not be resolved by adapting designs. Finally, in the late 1980s, automotive engineers rethought the problem from the beginning and began designing an electric car from the ground up with heavy consideration to aerodynamics, weight, and other energy efficiencies.
The space frame, seat frames, wheels, and body were designed for high strength for safety and the lightest possible weight. This meant new configurations that provide support for the components and occupants with minimal mass and use of high-tech materials including aluminum, magnesium, and advanced composite plastics. Because there is no exhaust system, the underside is made aerodynamic with a full belly pan. All extra details had to be eliminated while leaving the comforts drivers find desirable and adding new considerations unique to electric automobiles. One eliminated detail was the spare tire. The detail of the rod-like radio antennae was removed; it causes wind resistance that robs energy and uses energy to power it up and down. An added consideration was the pedestrian warning system; tests of prototypes showed that electric cars run so quietly that pedestrians don't hear them approach. Driver-activated flashing lights and beeps warn pedestrians that the car is approaching and work automatically when the car is in reverse. Windshields of solar glass were also an important addition to regulate the interior temperature and minimize the need for air conditioning and heating.
Among the many other design and engineering features that must be considered in producing electric cars are the following:
- Batteries that store energy and power the electric motor are a science of their own in electric car design, and many options are being studied to find the most efficient batteries that are also safe and cost effective. An electric motor that converts electrical energy from the battery and transmits it to the drive train. Both direct-current (DC) and alternating current (AC) motors are used in these traction or propulsion systems for electric cars, but AC motors do not use brushes and require less maintenance.
- A controller that regulates energy flow from the battery to the motor allows for adjustable speed. Resistors that are used for this purpose in other electric devices are not practical for cars because they absorb too much of the energy themselves. Instead, silicon-controlled rectifiers (SCRs) are used. They allow full power to go from the battery to the motor but in pulses so the battery is not overworked and the motor is not underpowered.
- Any kind of brakes can be used on electric automobiles, but regenerative braking systems are also preferred in electric cars because they recapture some of the energy lost during braking and channel it back to the battery system.
- Two varieties of chargers are needed. A full-size charger for installation in a garage is needed to recharge the electric car overnight, but a portable recharger (called a convenience recharger) is standard equipment for the trunk so the batteries can be recharged in an emergency or away from home or a charging station. For safety, an inductive charger was created for electric cars with a paddle that is inserted in the front end of the car. It uses magnetic energy to recharge the batteries and limit the potential for electrocution.
The Manufacturing Process
The manufacturing process required almost as much design consideration as the vehicle itself; and that design includes handcrafting and simplification as well as some high-tech approaches. The assemblers work in build-station teams to foster team spirit and mutual support, and parts are stored in modular units called creform racks of flexible plastic tubes and joints that are easy to fill and reshape for different parts. On the high-tech side, each station is equipped with one torque wrench with multiple heads; when the assembler locks on the appropriate size of head, computer controls for the machine select the correct torque setting for the fasteners that fit that head.
The body for the electric car is handcrafted at six work stations.
- 1 Parts of the aluminum space frame are put together in sections called subassemblies that are constructed of prefabricated pieces that are welded or glued together. The glue is an adhesive bonding material, and it provides a connection that is more durable and stiffer than welding. As the subassemblies for the undercarriage of the car are completed, they are bonded to each other until the entire underbody is finished.
- 2 The subassemblies for the upper part of the body are also bonded to make larger sections. The completed sections are similarly welded or glued until the body frame is finished. The body is added to the underbody. The adhesive used throughout staged assembly of the frame is then cured by conveying the body through a two-stage oven.
- 3 The roof is attached. Like other parts of the exterior, it has already been painted. The underbody and the rest of the frame are coated with protective sealants, and the finished body is moved to the general assembly area.
General assembly of the operating components and interior of the electric car is completed at eight other work stations.
- At the first assembly station, the first set of the electric car's complex electronics are put in place. This includes the body wiring and seating of the Power Electronics Bay which holds the Propulsion Control Module, integrated drive unit, and a small radiator. The integrated drive unit consists of the alternating current induction motor and a two-stage gear reduction and differential. These units are all preassembled in their
- The interior is outfitted. Flooring, seats, carpeting, and the console and dash are placed in the car. The process is simple because the instrument panel and console cover are made of molded, fiberglass reinforced urethane that has been coated with more urethane of finish quality and with a non-reflective surface. These two pieces are strong and don't need other supports, brackets, or mounting plates. Assembly is straight forward, and performance is superior because fewer pieces reduce possibilities for rattles and squeaks.
- At the third work station, the air conditioning, heating, and circulation system is inserted, and the system is filled.
- The battery pack is added. The T-shaped unit is seated by lifting the heavy pack using a special hoist up into the car. The pack is attached to the chassis, as are the axles complete with wheels and tires. With both batteries and the propulsion unit in place, the car no longer has to be moved from station to station on specially designed dollies. Instead, it is driven to the remaining work stations. The system is powered up and checked before it is driven to the next team.
- The windshield is installed and other fluids are added and checked. The door systems (complete with vinyl interiors, arm rests, electronics, and windows) are also attached, and all the connections are completed and checked. The exterior panels are added. Similar to the roof and doors, they have been prepared and painted before being brought to the work station. The final trim is attached to complete the upper exterior.
- At the final work station, the alignment is checked and adjusted, and the under-body panel is bolted into place. The process concludes with the last, comprehensive quality control check. Pressurized water is sprayed on the vehicle for eight minutes, and all the seals are checked for leaks. On a specialized test track, the car is checked for noises, squeaks, and rattles on a quality-based test drive. A lengthy and thorough visual inspection concludes the quality audit.
Industry has proven that work stations are a highly effective method of providing quality control throughout an assembly process. Each work station has two team members to support each other and provide internal checks on their part of the process. On a relatively small assembly line like this one for the electric car (75 assemblers in a General Motors plant), the workers all know each other, so there is also a larger team spirit that boosts pride and cooperation. Consequently, the only major quality control operation concludes the assembly process and consists of a comprehensive set of tests and inspections.
Unique to manufacture of the electric car, the operation of the car has been tested during the final assembly steps. The car has no exhaust system and emits no gases or pollutants, so, after the battery pack and propulsion unit have been installed, the car can be driven inside the plant. Proof that the product works several steps before it is finished is a reassuring quality check.
There are no byproducts from the manufacture of electric cars. Waste within the assembly factory also is minimal to nonexistent because parts, components, and subassemblies were all made elsewhere. Trimmings and other waste are recaptured by these suppliers, and most are recyclable.
Electric cars are critically important to the future of the automobile industry and to the environment; however, the form the electric car will ultimately take and its acceptance by the public are still uncertain. Consumption of decreasing oil supplies, concerns over air and noise pollution, and pollution caused (and energy consumed) by abandoned cars and the complications of recycling gasoline-powered cars are all driving forces that seem to be pushing toward the success of the electric car.
Where to Learn More
Hackleman, Michael. Electric Vehicles: Design and Build Your Own. Mariposa, CA: Earthmind/Peace Press, 1980.
Shacket, Sheldon R. The Complete Book of Electric Vehicles. Northbrook, IL: Domus Books, 1979.
Whitener, Barbara. The Electric Car Book. Louisville, KY: Love Street Books, 1981.
Associated Press. "Fuel-cell vehicles to take road test. "Daily Review (Hayward, California), 21 April 1999, p. 3.
Associated Press. "Honda dumps electric cars." Daily Review (Hayward, California), 30 April 1999.
General Motors. EVolution: The Official Publication of General Motors Advanced Technology Vehicles, 1997.
Hornblower, Margot. "Is this clean machine for real?"Time (December 15, 1997): 62+.
Electric Vehicle Association of the Americas. http://www.evaa.org/.
General Motors (GM) Satum EVI. http://www.gmev.com.
Honda EV Plus. http://www.honda1999.com/cars/ev.
i>Gillian S. Holmes