Battery Electric

Electric vehicles (Evs) use electric motors instead of an internal combustion engine to provide motive force. In a battery electric vehicle, the power is stored on board vehicles in rechargeable battery packs, which power electronic drive systems. The electricity required to recharge the batteries may be provided by utility-generated power or by any other available source of electricity. Utilities generate power from a variety of sources, including coal, natural gas, nuclear energy, hydropower, and renewables.

Professor Sibrandus Stratingh is credited with building the first model of an electric car in the Netherlands in 1835. The first practical electric road vehicles were made soon after by Robert Davidson in Scotland and by Thomas Davenport in the United States. Both inventors used non-rechargeable electric cells. When the Frenchmen Gaston Plante and Camille Faure invented (in 1865) and improved (in 1881) the electric storage battery, common use of electric vehicles became a possibility. In 1889, when the Belgian Camille Jentazy set a record of over 100 kph (62 miles) in a streamlined electric racing car, the potential of the electric car was brought to the world’s attention. By 1900, there were more electric than gas-powered cars on the road.

Before the widespread use of gasoline-fueled internal combustion engines and into the 1920’s, electricity, stored in lead-acid batteries, was a popular energy source for vehicles. Only in recent years has serious attention returned to electric vehicles for automobile transportation purposes. Battery technology for vehicles is now changing with the support of the U.S. Advanced Battery Consortium (USABC), a partnership of the Department of Energy, DaimlerChrysler, Ford, and General Motors. The USABC predicts use in the near future of four types of batteries: advanced lead-acid, nickel metal hydride, lithium-ion, and lithium-polymer.

When gasoline became the more popular fuel for on-road vehicles, EVs continued to be used off-road and for specialized functions. Even now, electric vehicles can be seen in factories and warehouses, where internal combustion engine exhaust could endanger worker health or damage products, and on golf courses, where their quiet operation provides a more relaxing environment. They are used in airports to move luggage, people, and planes; in law enforcement to enable a quiet approach by electric bicycle while expanding the range of the rider; on work sites to ferry employees between building; and on college campuses. To reduce pollution and noise in urban areas, cities are bringing back electric transit buses and trolleys.

Over 95 percent of the electricity used in the United States comes from domestic sources of energy. The nation’s existing power plants are capable of producing the electricity needed to operate millions of EVs if these vehicles are charged during off-peak hours. Widespread daytime charging of EVs will have an impact on the amount of electricity that will need to be produced.

According to the California Energy Commission, EVs are 0 to 25 percent more efficient than gasoline vehicles, and 10 to 30 percent less efficient than diesel vehicles. This comparison accounts for the entire fuel cycle – the energy used to extract, produce, and transport gasoline to the pump or to get the electricity to the plug, plus the energy used by the vehicle. Just taking the vehicle efficiency into account, an EV uses 66 percent of the electricity delivered to the charger for forward movement. An internal-combustion engine vehicle uses approximately 22 to 33 percent of the gasoline’s energy at the pump to move forward.

A battery EV has an electric motor instead of an engine, a battery pack and management system instead of a fuel tank, electronic controls instead of an ignition system, and the addition of a high-voltage electrical system. An EV is propelled when the electric motor receives sufficient electricity from the battery pack to provide the torque needed to turn the wheels at the rate desired. The accelerator pedal is connected to an electronic control module, which regulates the amount of current or voltage drawn from the battery system. Most EVs use regenerative braking – slowing the vehicle by capturing kinetic energy, converting it back into electrical energy, and then channeling it to the battery pack for later use.

Because an EV has few moving parts, service requirements are less than for conventional cars. An EV does not have an internal combustion engine, liquid fuel tank, fuel lines, carburetor, spark system, muffler, or pollution-control equipment. No timing belts, water pumps, radiators, fuel injectors, or tailpipes are required. No tune-ups, emission control adjustments, oil changes, or oil filter replacements are needed.

Lead-acid battery packs cost thousands of dollars and need replacement on average about every 30,000 miles or three years. Nickel-metal-hydride batteries may last up to 100,000 miles.

To promote safe use, vehicle manufacturers are using a number of disconnect systems in the high-voltage circuits, which isolate the rest of the rest of the vehicle from the battery voltage. Lethal levels of electricity may be present in the battery pack, however, so it should be treated with the same caution and respect as a full fuel tank in an internal combustion vehicle. In case of accidents, emergency response personnel will need special training to handle such hazards as exposure to high-voltage systems and possible leakage of flammable, toxic or corrosive battery chemicals.

A major difference between battery electric and internal-combustion-powered vehicles is the level of noise produced. Battery EVs are silent when idling and offer almost silent driving.

Acceleration, speed, and handling for well-designed EVs are equivalent to, or better than, those of comparable internal-combustion-powered vehicles. As of 1996, the world land-speed record for an electric car was just under 200 mph, and electric trains in Japan go even faster. In 1997, the top driving speed was 75 to 80 miles per hour, which may be limited by manufacturers in order to conserve battery power and extend the driving range. New battery EVs can accelerate from 0 to 60 mph in just 8.5 seconds and easily maintain highway speeds.

The average daily use of private vehicles in the major U.S. cities is 40 miles. Battery EVs average 40 to 125 miles per charge, depending on the vehicle’s weight, engineering and design features, and type of battery. Weather extremes, terrain, and use of accessories such as heating and air conditioning also affect the range.

When the battery powers the motor, it discharges; that is, an electrical current flows, reducing the amount of electric charge stored in chemical form in the battery. Recharging a battery reverses this process. An electric current is passed through the battery and reforms the active materials in the battery to their high-energy charge state. Most homes, government facilities, fleet garages, and businesses have enough electrical power to charge EVs, but additional sources of power on the street, at shopping malls, or in parking structures would make recharging more convenient for battery EV drivers.

The time needed for charging depends on the voltage of the electrical source, and the temperature, size, type and remaining state-of-charge of the batteries. Most EV batteries can be recharged using a grounded 120-volt, 15-amp, three-prong outlet found in most homes and buildings. This mode of charging is categorized as level 1 charging and takes 10 to 15 hours. Level 2 charging uses a 240-volt, 40-amp circuit, and takes 3 to 8 hours. The use of 480-volt equipment (level 3 charging) would enable recharging in as little as 5 to 10 minutes. This type of charging may be used in the future for public recharging sites.

Safely recharging an EV may require special hookups or upgrades to existing electrical outlets. To make the most efficient use of existing capacity, utilities will likely encourage home-based, overnight charging during off-peak hours.

Battery-powered electric vehicles produce no emissions in operation. This makes EVs a good choice for highly polluted urban areas, where human exposure to pollutants is greatest. EVs use virtually no energy while idling. In contrast, stop-and-go driving and idling increase the amount of pollutants per mile emitted from internal combustion engines. EVs can also help reduce the urban pollution that stems from running car air conditioners, carrying heavy loads or driving in cold temperatures – all of which increase pollution from internal combustion engines.

Emissions do occur at the power-generating facilities that supply the electricity needed to recharge the battery, and the amount of emissions depends on the efficiency of recharging the batteries and t he type of fuel used to produce power. An advantage of shifting emissions from tailpipes to power plants is that the emissions can be more easily controlled at a central location.

Electric drivetrains are more energy-efficient than are internal combustion engines. According to the California Energy Commission, EVs produce 90 percent fewer emissions than an internal combustion engine, even when emissions from power plants are considered.

The Argonne National Laboratory and the Union of Concerned Scientists (1995) have analyzed how the emissions of greenhouse gases would change if electric cars replaced gasoline-powered cars. The actual reduction of greenhouse gases depends on how the electricity used for charging is generated. The projected percentage of emissions reductions is shown below for each method of power production:

Coal-fired power plants: reductions of 17 to 22 percent.

Natural gas plants: reductions of 48 to 52 percent.

South Coast Air Basin of California, which relies on many sources of renewable energy: reduction of 71.2 percent.

Utilities using renewable energy sources (such as hydroelectric, wind, solar, or geothermal): reductions of almost 100 percent.

Nationwide: reductions of 31 to 46 percent.

No oil- or gasoline-caused water pollution is associated with EVs. Proper and safe disposal of batteries is important. Proper handling methods for lead-acid batteries are already in use, however, and more than 90 percent of lead-acid batteries are recycled in the United States. The acid is drained from the battery, cleaned, and recycled as electrolyte in new batteries; the lead is taken out and reused; even the plastic can be recycled. As other types of batteries are brought into use, similar environmentally responsible mechanisms for proper disposal and recycling will need to be developed and used.

Thanks to the Northeast Sustainable Energy Association (NESEA) for providing this information.

To learn more about electric vehicles, visit the Electric Vehicle Association of the Americas.  Easy Breathers has a profile of electric vehicles expert Michael Hackleman.