Electric cars

An electric car isa plug-in battery powered automobile which is propelled by electric motor(s).

Electric cars have the potential of significantly reducing city pollution by having zero tail pipe emissions.[1][2][3] Vehicle greenhouse gas savings depend on how the electricity is generated. With the current U.S. energy mix, using an electric car would result in a 30% reduction in carbon dioxide emissions.[4][5][6][7] Given the current energy mixes in other countries, it has been predicted that such emissions would decrease by 40% in the UK,[8] 19% in China,[9] and as little as 1% in Germany.[10][11]

Electric cars are expected to have a major impact in the auto industry[12][13] given advantages in city pollution, less dependence on oil, and expected rise in gasoline prices.[14][15][16] World governments are pledging billions to fund development of electric vehicles and their components. The U.S. has pledged US$2.4 billion in federal grants for electric cars and batteries.[17] China has announced it will provide US$15 billion to initiate an electric car industry.[18] Nissan CEO Carlos Ghosn has predicted that one in 10 cars globally will run on battery power alone by 2020.[19] Additionally a recent report claims that by 2020 electric cars and other green cars will take a third of the total of global car sales.[20]

Etymology

Electric cars are a variety of electric vehicle (EV); the term "electric vehicle" refers to any vehicle that uses electric motors for propulsion, while "electric car" generally refers to road-going automobiles powered by electricity. While an electric car's power source is not explicitly an on-board battery, electric cars with motors powered by other energy sources are generally referred to by a different name: an electric car powered by sunlight is a solar car, and an electric car powered by a gasoline generator is a form of hybrid car. Thus, an electric car that derives its power from an on-board battery pack is a form of battery electric vehicle (BEV). Most often, the term "electric car" is used to refer to pure battery electric vehicles.

[edit]History

German electric car, 1904, with the chauffeur on top

Main article: History of the electric vehicle

Electric cars enjoyed popularity between the mid-19th century and early 20th century, when electricity was among the preferred methods for automobile propulsion, providing a level of comfort and ease of operation that could not be achieved by the gasoline cars of the time. Advances in internal combustion technology soon rendered this advantage moot; the greater range of gasoline cars, quicker refueling times, and growing petroleum infrastructure, along with the mass production of gasoline vehicles by companies such as the Ford Motor Company, which reduced prices of gasoline cars to less than half that of equivalent electric cars, led to a decline in the use of electric propulsion, effectively removing it from important markets such as the United States by the 1930s. However, in recent years, increased concerns over the environmental impact of gasoline cars, along with reduced consumer ability to pay for fuel for gasoline cars, and the prospect of peak oil, has brought about renewed interest in electric cars, which are perceived to be more environmentally friendly and cheaper to maintain and run, despite high initial costs. Electric cars currently enjoy relative popularity in countries around the world, though they are notably absent from the roads of the United States, where electric cars briefly re-appeared in the late 90s as a response to changing government regulations.

1912 Detroit Electric advertisement

[edit]1890s to 1900s: Early history

Before the pre-eminence of internal combustion engines, electric automobiles held many speed and distance records. Among the most notable of these records was the breaking of the 100 km/h (62 mph) speed barrier, by Camille Jenatzy on April 29, 1899 in his 'rocket-shaped' vehicle Jamais Contente, which reached a top speed of 105.88 km/h (65.79 mph). Before the 1920s, electric automobiles were competing with petroleum-fueled cars for urban use of a quality service car.[21]

Thomas Edison and an electric car in 1913 (courtesy of the National Museum of American History)

Proposed as early as 1896 in order to overcome the lack of recharging infrastructure, a exchangeable battery service was first put into practice by Hartford Electric Light Company for electric trucks. The vehicle owner purchased the vehicle from General Electric Company (GVC) without a battery and the electricity was purchased from Hartford Electric through an exchangeable battery. The owner paid a variable per-mile charge and a monthly service fee to cover maintenance and storage of the truck. The service was provided between 1910 to 1924 and during that period covered more than 6 million miles. Beginning in 1917 a similar service was operated in Chicago for owners of Milburn Light Electric cars who also could buy the vehicle without the batteries.[22]

In 1897, electric vehicles found their first commercial application in the U.S. as a fleet of electrical New York City taxis, built by the Electric Carriage and Wagon Company of Philadelphia. Electric cars were produced in the US by Anthony Electric, Baker, Columbia, Anderson, Edison [disambiguation needed], Studebaker, Riker, Milburn, and others during the early 20th century.

The low range of electric cars meant they could not make use of the new highways to travel between cities

Despite their relatively slow speed, electric vehicles had a number of advantages over their early-1900s competitors. They did not have the vibration, smell, and noise associated with gasoline cars. They did not require gear changes, which for gasoline cars was the most difficult part of driving. Electric cars found popularity among well-heeled customers who used them as city cars, where their limited range proved to be even less of a disadvantage. The cars were also preferred because they did not require a manual effort to start, as did gasoline cars which featured a hand crank to start the engine. Electric cars were often marketed as suitable vehicles for women drivers due to this ease of operation.

The Henney Kilowatt, a 1961 production electric car based on the Renault Dauphine

In 1911, the New York Times stated that the electric car has long been recognized as "ideal" because it was cleaner, quieter and much more economical than gasoline-powered cars. Reporting this in 2010, the Washington Post commented that "the same unreliability of electric car batteries that flummoxed Thomas Edison persists today."[23]

[edit]1990s to present: Revival of mass interest

The General Motors EV1, one of the cars introduced as a result of the California Air Resources Board (CARB) mandate, had a range of 160 mi (260 km) with NiMH batteries in 1999.

The Toyota RAV4 EV is powered by twenty-four 12 volt NiMH batteries, with an operational cost equivalent of over 165 mpg-US (1.43 L/100 km; 198 mpg-imp) at 2005 US gasoline prices.

Electric Peugeot 106

At the 1990 Los Angeles Auto Show, General Motors President Roger Smith unveiled the GM Impact electric concept car, along with the announcement that GM would build electric cars for sale to the public.

In the early 1990s, the California Air Resources Board (CARB), the government of California's "clean air agency", began a push for more fuel-efficient, lower-emissions vehicles, with the ultimate goal being a move to zero-emissions vehicles such as electric vehicles.

In 2000, Hybrid Technologies, later renamed Li-ion Motors, started manufacturing electric cars in Mooresville, North Carolina. There has been increasing controversy with Li-ion Motors though due to the ongoing 'Lemon issues' regarding their product.[24] and their attempt to cover it up.[25] California electric car maker Tesla Motors began development in 2004 on the Tesla Roadster, which was first delivered to customers in 2008. The Roadster remains the only highway-capable EV in serial production and available for sale today. Senior leaders at several large automakers, including Nissan and General Motors, have stated that the Roadster was a catalyst which demonstrated that there is pent-up consumer demand for more efficient vehicles. GM Vice Chairman Bob Lutz said in 2007 that the Tesla Roadster inspired him to push GM to develop the Chevrolet Volt, a plug-in hybrid sedan prototype that aims to reverse years of dwindling market share and massive financial losses for America's largest automaker.[26] In an August 2009 edition of The New Yorker, Lutz was quoted as saying, "All the geniuses here at General Motors kept saying lithium-ion technology is 10 years away, and Toyota agreed with us -- and boom, along comes Tesla. So I said, 'How come some tiny little California startup, run by guys who know nothing about the car business, can do this, and we can't?' That was the crowbar that helped break up the log jam."[27]

The Nissan LEAF introduced in Japan and the United States in 2010 is the first all electric, zero emission five door family hatchback to be produced for the mass market from a major manufacturer.[28][29] Lithium-ion battery technology, smooth body shell and advanced regenerative braking give the LEAF performance comparable to an ICE, a range of around 160 km and the capability to reach 80% recharge levels in under 30 minutes.[30] In June 2009 BMW began field testing in the U.S. of its all-electric Mini E,[31] through the leasing of 500 cars to private users in Los Angeles and the New York/New Jersey area.[32][33] A similar field test was launched in the U.K. in December 2009 with a fleet of more than forty Mini E cars.[34] General Electric plans to buy 25,000 electric vehicles and convert more than half its fleet to electricity by 2015.[35]

[edit]Comparison with internal combustion engine vehicles

An important goal for electric vehicles is overcoming the disparity between their costs of development, production, and operation, with respect to those of equivalent internal combustion engine vehicles (ICEVs).

[edit]Price

Electric cars are generally more expensive than gasoline cars. The primary reason is the high cost of car batteries. US and British car buyers seem to be unwilling to pay more for an electric car.[36][37] This prohibits the mass transition from gasoline cars to electric cars. A survey taken by Nielsen for the Financial Times has shown that 65 percent of Americans and 76 percent of Britons are not willing pay more for an electric car above the price of a gasoline car.[38] also a report by J.D. Power and Associates claims that about 50 percent of U.S. car buyers are not even willing to spent more than US$5,000 on a green vehicle above the price of a petrol car despite their concern about the environment.[39]

The Nissan LEAF is the most affordable five door family electric car in the U.S. at a price of US$32,780 going down to US$25,280 after federal tax rebate of US$7,500, going further down to US$20,280 after the US$5,000 tax rebate in California and similar incentives in other states.

The Renault Fluence Z.E. five door family saloon electric car will be priced at less than US$20,000 before any U.S. federal and state tax rebates are applied.[40] It will be sold without the battery thus the significant price difference. The customer will buy the Renault Fluence Z.E. with a contract to lease the battery from the company Better Place.

The electric car company Tesla Motors is using laptop battery technology for the battery packs of their electric cars that are 3 to 4 times cheaper than dedicated electric car battery packs that other auto makers are using. While dedicated battery packs cost $700-$800 per kilowatt hour, battery packs using small laptop cells cost about $200. That could potentially drive down the cost of electric cars that are using Tesla's battery technology such as the Toyota RAV4 EV and the Smart ED as well as their own upcoming 2014 models such as the Model X.[41][42]

[edit]Running costs and Maintenance

Most of the running cost of an electric vehicle can be attributed to the maintenance and replacement of the battery pack because an electric vehicle has only around 5 moving parts in its engine, compared to a gasoline car that has hundreds of parts in its internal combustion engine.[43] Electric cars have expensive batteries that must be replaced but otherwise incur very low maintenance costs.. Particularly in the case of current Lithium based designs.

To calculate the cost per kilometer of an electric vehicle it is therefore necessary to assign a monetary value to the wear incurred on the battery. This can be difficult due to the fact that it will have a slightly lower capacity each time it is charged and is only considered to be at the end of its life when the owner decides its performance is no longer acceptable. Even then an 'end of life' battery is not completely worthless as it can be re-purposed, recycled or used as a spare.

Since a battery is made of many individual cells that do not necessarily wear evenly periodically replacing the worst of these can retain the vehicle's range.

The Tesla Roadster's very large battery pack is expected to last seven years with typical driving and costs US$12,000 when pre-purchased today.[44][45] Driving 40 miles (64 km) per day for seven years or 102,200 miles (164,500 km) leads to a battery consumption cost of US$0.1174 per 1 mile (1.6 km) or US$4.70 per 40 miles (64 km). The company Better Place provides another cost comparison as they anticipate meeting contractual obligations to deliver batteries as well as clean electricity to recharge the batteries at a total cost of US$0.08 per 1 mile (1.6 km) in 2010, US$0.04 per mile by 2015 and US$0.02 per mile by 2020.[46] 40 miles (64 km) of driving would initially cost US$3.20 and fall over time to US$0.80.

In 2010 the US government estimated that a battery with a 100 miles (160 km) range would cost about US$33,000. Concerns remain about durability and longevity of the battery.[47]

Nissan estimates that the Leaf's 5 year operating cost will be US$1,800 versus US$6,000 for a gasoline car.[48] The documentary film Who Killed the Electric Car?[49] shows a comparison between the parts that require replacement in a gasoline powered cars and EV1s, with the garages stating that they bring the electric cars in every 5,000 mi (8,000 km), rotate the tires, fill the windshield washer fluid and send them back out again.

[edit]Electricity vs. Fuel

"Fuel" cost comparison: the Tesla Roadster sport car's plug-to-wheel energy use is 280 W·h/mi. In Northern California, the local electric utility company PG&E says that "The E-9 rate is mandatory for those customers that are currently on a residential electric rate and who plan on refueling an EV on their premises."[50] Combining these two facts implies that driving a Tesla Roadster 40 miles (64 km) a day would use 11.2 kW·h of electricity costing between US$0.56 and US$3.18 depending on the time of day chosen for recharging.[50] For comparison, driving an internal combustion engine-powered car the same 40 miles (64 km), at a mileage of 25 miles per US gallon (9.4 L/100 km; 30 mpg-imp), would use 1.6 US gallons (6.1 l; 1.3 imp gal) of fuel and, at a cost of US$3 per 1 US gallon (3.8 l; 0.83 imp gal), would cost US$4.80.

The Tesla Roadster uses about 17.4 kW·h/100 km (0.63 MJ/km; 0.280 kW·h/mi),[51] the EV1 used about 11 kW·h/100 km (0.40 MJ/km; 0.18 kW·h/mi).[52]

[edit]Range

"Range anxiety" is a reason that many automakers marketed EVs as "daily drivers" suitable for city trips and other short hauls.[53] The average American drives less than 40 miles (64 km) per day; so the GM EV1 would have been adequate for the daily driving needs of about 90% of U.S. consumers.[49]

The Tesla Roadster gets 245 miles (394 km) per charge;[54] more than double that of prototypes and evaluation fleet cars currently on the roads.[55] The Roadster can be fully recharged in about 3.5 hours from a 220-volt, 70-amp home outlet.[56]

One way automakers can extend the short range of electric vehicles is by building them with battery switch technology. An EV with battery switch technology and a 100 miles (160 km) driving range will be able to go to a battery switch station and switch a depleted battery with a fully charged one in 59.1 seconds[57] giving the EV an additional 100 miles (160 km) driving range. The process is cleaner and faster than filling a tank with gasoline and the driver remains in the car the entire time.[58] As of late 2010 there are only 2 companies with plans to integrate battery switching technology to their electric vehicles.[59][60][61] The company Better Place is already operating a battery switch station in Japan up to the end of 2010[62] and announced a commitment to open four battery switch stations in the US from San Francisco to San Jose in California.[63]

Another way is the installation of DC Fast Charging stations with high-speed charging capability from three-phase industrial outlets so that consumers could recharge the 100 mile battery of their electric vehicle to 80 percent in about 30 minutes.[64][65] A nationwide fast charging infrastructure is currently being deployed in the US that by 2013 will cover the entire nation.[66] DC Fast Chargers are going to be installed at 45 BP and ARCO locations and will be made available to the public as early as March 2011.[67] The EV Project will deploy charge infrastructure in 16 cities and major metropolitan areas in six states.[68][69] Nissan has announced that 200 of it's dealers in Japan will install fast chargers for the December 2010 launch of its Leaf EV, with the goal of having fast chargers everywhere in Japan within a 25 mile radius.[70]

On April 21, 2010, Sanyo announced that it performed a 555.6 km (345.2 mile) travel from Tokyo to Osaka on a single charge with an electric Li-Ion batteries powered Daihatsu Mira.[71] May 25, 2010, Sanyo announced breaking its own record with a 1003 km (623 mile) travel. It took 27.5 hours at an average speed of 25 mph (40 km/h) at a training school for auto racers in Ibaraki[72]

From July to August 2010, a team of engineering students from the Imperial London College in the UK drove the Pan American Highway, a distance of 48,276 km (29,800 miles) in the SRZero.[73]

At the same time, a team of engineering students from the University of British Columbia near Vancouver drove across Canada in 13 days, a distance of 8,000 km (5,000 miles) within a limited budget and with no support vehicle.[74] The teams each used approximately 50 kWH of Thundersky lithium cells to achieve a range of between 350 and 600 km (217 and 372 miles) per charge. Both teams used high power chargers capable of a 4-hour charge time.

[edit]Pollution

Sources of electricity in the U.S. in 2009.[6]

Electric cars produce no pollution at the tailpipe, but their use increases demand for electricity generation. The amount of carbon dioxide emitted depends on the emission intensity of the power source used to charge the vehicle, the efficiency of the said vehicle and the energy wasted in the charging process.

For mains electricity the emission intensity varies significantly per country and within a particular country it will vary depending on the time of day and even over the course of the year[75] depending on the availability of renewable sources and the efficiency of the fossil fuel-based generation used at a given time.[76] Charging a vehicle using off-grid renewable energy yields very low carbon intensity (only that to produce and install the off-grid generation system e.g. domestic wind turbine).

An EV recharged from the existing US grid electricity emits about 115 grams of CO2 per kilometer driven (6.5 oz(CO2)/mi), whereas a conventional US-market gasoline powered car emits 250 g(CO2)/km (14 oz(CO2)/mi) (most from its tailpipe, some from the production and distribution of gasoline).[77] The savings are questionable relative to hybrid or diesel cars, (according to official British government testing, the most efficient European market cars are well below 115 grams of CO2 per kilometer driven, although a study in Scotland gave 149.5g CO2/km as the average for new cars in the UK[78]), but would be more significant in countries with cleaner electric infrastructure. In a worst case scenario where incremental electricity demand would be met exclusively with coal, a 2009 study conducted by the WWF, World Wide Fund for Nature, and IZES found that a mid-size EV would emit roughly 200 g(CO2)/km (11 oz(CO2)/mi), compared with an average of 170 g(CO2)/km (9.7 oz(CO2)/mi) for a gasoline powered compact car.[79] This study concluded that introducing 1 million EV cars to Germany would, in the best case scenario, only reduce CO2 emissions by 0.1%, if nothing is done to upgrade the electricity infrastructure or manage demand.[79]

[edit]Acceleration and drivetrain design

Electric motors can provide high power to weight ratios, and batteries can be designed to supply the large currents to support these motors.

Although some electric vehicles have very small motors, 15 kW (20 hp) or less and therefore have modest acceleration, many electric cars have large motors and brisk acceleration. In addition, the relatively constant torque of an electric motor, even at very low speeds tends to increase the acceleration performance of an electric vehicle relative to that of the same rated motor power internal combustion engine. Another early solution was American Motors’ experimental Amitron piggyback system of batteries with one type designed for sustained speeds while a different set boosted acceleration when needed.

Electric vehicles can also use a direct motor-to-wheel configuration which increases the amount of available power. Having multiple motors connected directly to the wheels allows for each of the wheels to be used for both propulsion and as braking systems, thereby increasing traction. In some cases, the motor can be housed directly in the wheel, such as in the Whispering Wheel design, which lowers the vehicle's center of gravity and reduces the number of moving parts. When not fitted with an axle, differential, or transmission, electric vehicles have less drivetrain rotational inertia.

When the foot is lifted from the accelerator of an ICE, engine braking causes the car to slow. An EV would coast under these conditions, and applying mild regenerative braking instead provides a more familiar response.

A gearless or single gear design in some EVs eliminates the need for gear shifting, giving such vehicles both smoother acceleration and smoother braking. Because the torque of an electric motor is a function of current, not rotational speed, electric vehicles have a high torque over a larger range of speeds during acceleration, as compared to an internal combustion engine. As there is no delay in developing torque in an EV, EV drivers report generally high satisfaction with acceleration.

For example, the Venturi Fetish delivers supercar acceleration despite a relatively modest 220 kW (295 hp), and top speed of around 160 km/h (100 mph). Some DC motor-equipped drag racer EVs, have simple two-speed transmissions to improve top speed.[80] The Tesla Roadster 2.5 Sport can accelerate from 0 to 60 mph (97 km/h) in 3.7 seconds with a motor rated at 215 kW (288 hp).[81]

Also the Wrightspeed X1 Prototype created by Wrightspeed Inc is the worlds fastest street legal electric car.[82] With an acceleration of 0-60 mph in 2.9 seconds[83] the X1 has bested some of the worlds fastest sports cars. [84]

[edit]Energy efficiency

Main articles: Fuel efficiency, Electrical efficiency, Thermal efficiency, and Energy conversion efficiency

Internal combustion engines are relatively inefficient at converting on-board fuel energy to propulsion as most of the energy is wasted as heat. On the other hand, electric motors are more efficient in converting stored energy into driving a vehicle, and electric drive vehicles do not consume energy while at rest or coasting, and some of the energy lost when braking is captured and reused through regenerative braking, which captures as much as one fifth of the energy normally lost during braking.[85][86] Typically, conventional gasoline engines effectively use only 15% of the fuel energy content to move the vehicle or to power accessories, and diesel engines can reach on-board efficiencies of 20%, while electric drive vehicles have on-board efficiency of around 80%.[85]

Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi).[52][87] Approximately 20% of this power consumption is due to inefficiencies in charging the batteries. Tesla Motors indicates that the vehicle efficiency (including charging inefficiencies) of their lithium-ion battery powered vehicle is 12.7 kW·h/100 km (0.21 kW·h/mi) and the well-to-wheels efficiency (assuming the electricity is generated from natural gas) is 24.4 kW·h/100 km (0.39 kW·h/mi).[88]

[edit]Safety

The safety issues of BEVs are largely dealt with by the international standard ISO 6469. This document is divided in three parts dealing with specific issues:

On-board electrical energy storage, i.e. the battery

Functional safety means and protection against failures

Protection of persons against electrical hazards.

Firefighters and rescue personnel receive special training to deal with the higher voltages and chemicals encountered in electric and hybrid electric vehicle accidents. While BEV accidents may present unusual problems, such as fires and fumes resulting from rapid battery discharge, there is apparently no available information regarding whether they are inherently more or less dangerous than gasoline or diesel internal combustion vehicles which carry flammable fuels.

[edit]Vehicle safety

Great effort is taken to keep the mass of an electric vehicle as low as possible, in order to improve the EV's range and endurance. Despite these efforts, the high density and weight of the electric batteries usually results in an EV being heavier than a similar equivalent gasoline vehicle leading to less interior space, and longer braking distances. However, in a collision, the occupants of a heavy vehicle will, on average, suffer fewer and less serious injuries than the occupants of a lighter vehicle; therefore, the additional weight brings safety benefits[89] despite having a negative effect on the car's performance.[90] An accident in a 2,000 lb (900 kg) vehicle will on average cause about 50% more injuries to its occupants than a 3,000 lb (1,400 kg) vehicle.[91][92] In a single car accident,[citation needed] and for the other car in a two car accident, the increased mass causes an increase in accelerations and hence an increase in the severity of the accident. Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires.[93][94][95] Many electric cars have a small, light and fragile body, though, and therefore offer inadequate safety protection. Because of this, the Insurance Institute for Highway Safety in America had condemned the use of such vehicles.[96]

[edit]Hazard to pedestrians

See also: Electric vehicle warning sounds

At low speeds, electric cars produced less roadway noise as compared to vehicles propelled by a internal combustion engine. Blind people or the visually impaired consider the noise of combustion engines a helpful aid while crossing streets, hence electric cars and hybrids could pose an unexpected hazard.[97][98] Tests have shown that this is a valid concern, as vehicles operating in electric mode can be particularly hard to hear below 20 mph (30 km/h) for all types of road users and not only the visually impaired. At higher speeds the sound created by tire friction and the air displaced by the vehicle start to make sufficient audible noise.[98]

The US Congress, the European Commission and the Government of Japan are exploring legislation to establish a minimum level of sound for hybrids and plug-in electric vehicles when operating in electric mode, so that blind people and other pedestrians and cyclists can hear them coming and detect from which direction they are approaching.[98][99] The Nissan Leaf is the first electric car to include Nissan's Vehicle Sound for Pedestrians system, which will include one sound for forward motion and another for reverse.[100][101]

[edit]Cabin heating and cooling

Electric vehicles generate very little waste heat and resistance electric heat may have to be used to heat the interior of the vehicle if heat generated from battery charging/discharging can not be used to heat the interior.

While heating can be simply provided with an electric resistance heater, higher efficiency and integral cooling can be obtained with a reversible heat pump (this is currently implemented in the hybrid Toyota Prius). Positive Temperature Coefficient (PTC) junction cooling[102] is also attractive for its simplicity - this kind of system is used for example in the Tesla Roadster.

However some electric cars, for example the Citroën Berlingo Electrique, use an auxiliary heating system (for example gasoline-fueled units manufactured by Webasto or Eberspächer). Cabin cooling can be augmented with solar power, most simply and effectively by inducting outside air to avoid extreme heat buildup when the vehicle is closed and parked in the sunlight (such cooling mechanisms are available as aftermarket kits for conventional vehicles). Two models of the 2010 Toyota Prius include this feature as an option.[103]

[edit]Batteries

Prototypes of 75 watt-hour/kilogram lithium-ion polymer battery. Newer lithium-ion cells can provide up to 130 W·h/kg and last through thousands of charging cycles.

Main article: Electric vehicle battery

Finding the economic balance of range against performance, energy density, and accumulator type versus cost challenges every EV manufacturer.

While most current highway-speed electric vehicle designs focus on lithium-ion and other lithium-based variants a variety of alternative batteries can also be used. Lithium based batteries are often chosen for their high power and energy density but have a limited shelf-life and cycle lifetime which can significantly increase the running costs of the vehicle. Variants such as Lithium iron phosphate and Lithium-titanate attempt to solve the durability issues with traditional lithium-ion batteries.

Other battery technologies include:

Lead acid batteries are still the most used form of power for most of the electric vehicles used today. The initial construction costs are significantly lower than for other battery types, and while power output to weight is poorer than other designs, range and power can be easily added by increasing the number of batteries.[104]

NiCd - Largely superseded by NiMH

Nickel metal hydride (NiMH)

Nickel iron battery - Known for its comparatively long lifetime and low power density

Several battery technologies are also in development such as:

Zinc-air battery

Molten salt battery

Zinc-bromine flow batteries or Vanadium redox batteries can be refilled, instead of recharged, saving time. The depleted electrolyte can be recharged at the point of exchange, or taken away to a remote station.

[edit]Travel range before recharging

The range of an electric car depends on the number and type of batteries used. The weight and type of vehicle, and the performance demands of the driver, also have an impact just as they do on the range of traditional vehicles. The range of an electric vehicle conversion depends on the battery type:

[edit]Replacing

The Renault Fluence Z.E. plans to have easily replaceable batteries. Available in 2011 in Europe.

An alternative to quick recharging is to exchange the drained or nearly drained batteries (or battery range extender modules) with fully charged batteries, rather as stagecoach horses were changed at coaching inns. Batteries could be leased or rented instead of bought, and then maintenance deferred to the leasing or rental company, and ensures availability.

Renault announced at the 2009 Frankfurt Motor Show that they have sponsored a network of charging stations and plug-in plug-out battery swap stations.[105] Other vehicle manufacturers and companies are also investigating the possibility.

Replaceable batteries were used in the electric buses at the 2008 Summer Olympics.[106]

[edit]Vehicle-to-grid: uploading and grid buffering

Main article: Vehicle-to-grid

See also: Economy 7 and load balancing (electrical power)

A Smart grid allows BEVs to provide power to the grid, specifically:

During peak load periods, when the cost of electricity can be very high. These vehicles can then be recharged during off-peak hours at cheaper rates while helping to absorb excess night time generation. Here the batteries in the vehicles serve as a distributed storage system to buffer power.

During blackouts, as an emergency backup supply.

Such a system will not be widely feasible until the cycle durability of battery packs is significantly increased.[dubious – discuss]

[edit]Lifespan

Battery life should be considered when calculating the extended cost of ownership, as all batteries eventually wear out and must be replaced. The rate at which they expire depends on the type of battery technology and how they are used - many types of batteries are damaged by depleting them beyond a certain level. For example deep cycle lead-acid batteries generally should not be discharged below 20% capacity and lithium-ion batteries degrade faster when stored at higher temperatures.

[edit]NiMH battery durability

In real world use, some fleet Toyota RAV4 EVs, using NiMH batteries will exceed 160 000 km (100,000 mi), and have had little degradation in their daily range.[107] Quoting that report's concluding assessment:

The five-vehicle test is demonstrating the long-term durability of Nickel Metal Hydride batteries and electric drive trains. Only slight performance degradation has been observed to-date on four out of five vehicles.... EVTC test data provide strong evidence that all five vehicles will exceed the 100,000-mile (160,000 km) mark. SCE’s positive experience points to the very strong likelihood of a 130,000-to-150,000-mile (210,000 to 240,000 km) Nickel Metal Hydride battery and drive-train operational life. EVs can therefore match or exceed the lifecycle miles of comparable internal combustion engine vehicles.

In June 2003 the 320 RAV4 EVs of the SCE fleet were used primarily by meter readers, service managers, field representatives, service planners and mail handlers, and for security patrols and carpools. In five years of operation, the RAV4 EV fleet had logged more than 6.9 million miles, eliminating about 830 tons of air pollutants, and preventing more than 3,700 tons of tailpipe CO2 emissions. Given the successful operation of its EVs to-date, SCE plans to continue using them well after they all log 100,000 miles (160,000 km).

[edit]Nickel Iron battery durability

Jay Leno's 1909 Baker Electric still operates on its original Edison cells, however current-generation high energy density Lithium-ion batteries have a significantly shorter lifetime. Battery replacement costs of BEVs may be partially offset by the elimination of some regular maintenance, such as oil and filter changes required for ICEVs, and by the greater reliability of BEVs due to their fewer moving parts. By the time batteries do need replacement it might be possible to replace them with later generation ones which may offer better performance characteristics.

[edit]Future

The future of battery electric vehicles depends primarily upon the cost and availability of batteries with high specific energy, power density, short charge time and long life, as all other aspects such as motors, motor controllers, and chargers are fairly mature and cost-competitive with internal combustion engine components. Li-ion, Li-poly and zinc-air batteries have demonstrated specific energy high enough to deliver range and recharge times comparable to conventional vehicles.[citation needed] Diarmuid O'Connell, VP of Business Development at Tesla Motors, estimates that by the year 2020 30% of the cars driving on the road will be battery, electric or plug-in hybrid.[108]

It is estimated that there are sufficient lithium reserves to power 4 billion electric cars.[citation needed]

[edit]Other methods of energy storage

Experimental supercapacitors and flywheel energy storage devices offer comparable storage capacity, faster charging, and lower volatility. They have the potential to overtake batteries as the preferred rechargeable storage for EVs.[109][110] The FIA included their use in its sporting regulations of energy systems for Formula One race vehicles in 2007 (for supercapacitors) and 2009 (for flywheel energy storage devices).

[edit]Solar cars

Main articles: Solar taxi and Solar vehicle

Solar cars are electric cars that derive most or all of their electricity from built in solar panels. After the 2005 World Solar Challenge established that solar race cars could exceed highway speeds, the specifications were changed to provide for vehicles that with little modification could be used for transportation.

[edit]Charging

Charging station at Rio de Janeiro, Brazil. This station is run by Petrobras and uses solar energy.

Main article: charging station

Batteries in BEVs must be periodically recharged (see also Replacing, above). BEVs most commonly charge from the power grid (at home or using a street or shop charging station), which is in turn generated from a variety of domestic resources; such as coal, hydroelectricity, nuclear and others. Home power such as roof top photovoltaic solar cell panels, micro hydro or wind may also be used and are promoted because of concerns regarding global warming.

[edit]Level 1, 2, and 3 charging

Around 1998 the California Air Resources Board classified levels of charging power that have been codified in title 13 of the California Code of Regulations, the U.S. 1999 National Electrical Code section 625 and SAE International standards.

Level Original definition[111] Coulomb Technologies' definition[112] Connectors

Level 1 AC energy to the vehicle's on-board charger; from the most common U.S. grounded household receptacle, commonly referred to as a 120 volt outlet. 120 V AC; 16 A (= 1.92 kW) SAE J1772 (16.8 kW)

Level 2 AC energy to the vehicle's on-board charger;208-240 volt, single phase. The maximum current specified is 32 amps (continuous) with a branch circuit breaker rated at 40 amps. Maximum continuous input power is specified as 7.68 kW (= 240V x 32A*). 208-240 V AC;

12 A to 80 A (= 2.5 to 19.2 kW) SAE J1772 (16.8 kW)

IEC 62196 (44 kW)

Magne Charge

IEC 60309 16 A (3.8 kW)

Level 3 DC energy from an off-board charger; there is no minimum energy requirement but the maximum current specified is 400 amps and 240 kW continuous power supplied. very high voltages (300-600 V DC); very high currents (100s of Amperes) CHΛdeMO (62.5 kW)

.* or potentially 208V x 37A, out of the strict specification but within circuit breaker and connector/cable power limits. Alternatively, this voltage would impose a lower power rating of 6.7 kW at 32A.

The term "Level 3" has also been used by the SAE J1772 Connector Standard Committee for a possible future higher-power AC fast charging connector.[113] SAE has not approved standards for either higher-power connector.[114]

[edit]Connectors

Most electric cars have used conductive coupling to supply electricity for recharging after the California Air Resources Board settled on the SAE J1772-2001 standard[115] as the charging interface for electric vehicles in California in June 2001.[116]

Another approach is inductive charging using a non-conducting "paddle" inserted into a slot in the car. Delco Electronics developed the Magne Charge inductive charging system around 1998 for the General Motors EV1 and it was also used for the Chevrolet S-10 EV and Toyota RAV4 EV vehicles.

[edit]Regenerative braking

Main article: Regenerative braking

Using regenerative braking, a feature which is present on many hybrid electric vehicles, approximately 20% of the energy usually lost in the brakes is recovered to recharge the batteries.[86]

[edit]Charging time

More electrical power to the car reduces charging time. Power is limited by the capacity of the grid connection, and, for level 1 and 2 charging, by the power rating of the car's on-board charger. A normal household outlet is between 1.5 kW (in the US, Canada, Japan, and other countries with 110 volt supply) to 3 kW (in countries with 230V supply). The main connection to a house may sustain 10, 15 or even 20 kW in addition to "normal" domestic loads - though it would be unwise to use all the apparent capability - and special wiring can be installed to use this. As examples of on-board chargers, the Nissan Leaf at launch has a 3.3 kW charger[117] and the Tesla Roadster appears to accept 16.8 kW (240V at 70A) from the Tesla Home Connector.[118] These power numbers are small compared to the effective power delivery rate of an average petrol pump, about 5,000 kW. Even if the electrical supply power can be increased, most batteries do not accept charge at greater than their charge rate ("1C"), because high charge rates have an adverse effect on the discharge capacities of batteries.[119] Despite these power limitations, plugging in to even the least-powerful conventional home outlet provides more than 15 kilowatt-hours of energy overnight, sufficient to propel most electric cars more than 70 kilometres (43 mi) (see Energy efficiency below).

[edit]Faster charging

In 1995, some charging stations charged BEVs in one hour. In November 1997, Ford purchased a fast-charge system produced by AeroVironment called "PosiCharge" for testing its fleets of Ranger EVs, which charged their lead-acid batteries in between six and fifteen minutes. In February 1998, General Motors announced a version of its "Magne Charge" system which could recharge NiMH batteries in about ten minutes, providing a range of 60 to 100 mi (100 to 160 km).[120]

In 2005, mobile device battery designs by Toshiba were claimed to be able to accept an 80% charge in as little as 60 seconds.[121] Scaling this specific power characteristic up to the same 7 kW·h EV pack would result in the need for a peak of 340 kW from some source for those 60 seconds. It is not clear that such batteries will work directly in BEVs as heat build-up may make them unsafe.

Altairnano's NanoSafe batteries can be recharged in several minutes, versus hours required for other rechargeable batteries. A NanoSafe cell can be charged to around 95% charge capacity in approximately 10 minutes.[122][123]

Japanese company, JFE Engineering, has developed a quick charger that it claims needs three minutes for a 50% charge, or five minutes for a 70% charge.[124]

Most people do not usually require fast recharging because they have enough time, 30 minutes to six hours (depending on discharge level) during the work day or overnight at home to recharge. The charging does not require attention so it takes only a few seconds of the owner's time for plugging and unplugging the charging source. BEV drivers frequently prefer recharging at home, avoiding the inconvenience of visiting a public charging station. Some workplaces provide special parking bays for electric vehicles with chargers provided - sometimes powered by solar panels. In colder areas such as Finland, some northern US states and Canada there already exists some infrastructure for public power outlets, in parking garages and at parking meters, provided primarily for use by block heaters and set with circuit breakers that prevent large current draws for other uses.[125]

[edit]Hobbyists, conversions, and racing

Eliica prototype

The full electric Formula Student car of the Eindhoven University of Technology

Hobbyists often build their own EVs by converting existing production cars to run solely on electricity. There is a cottage industry supporting the conversion and construction of BEVs by hobbyists. Universities such as the University of California, Irvine even build their own custom electric or hybrid-electric cars from scratch.

Short-range battery electric vehicles can offer the hobbyist comfort, utility, and quickness, sacrificing only range. Short-range EVs may be built using high-performance lead–acid batteries, using about half the mass needed for a 100 to 130 km (60 to 80 mi) range. The result is a vehicle with about a 50 km (30 mi) range, which, when designed with appropriate weight distribution (40/60 front to rear), does not require power steering, offers exceptional acceleration in the lower end of its operating range, and is freeway capable and legal. But their EVs are expensive due to the higher cost for these higher-performance batteries. By including a manual transmission, short-range EVs can obtain both better performance and greater efficiency than the single-speed EVs developed by major manufacturers. Unlike the converted golf carts used for neighborhood electric vehicles, short-range EVs may be operated on typical suburban throughways (where 60–80 km/h / 35-50 mph speed limits are typical) and can keep up with traffic typical on such roads and the short "slow-lane" on-and-off segments of freeways common in suburban areas.

Faced with chronic fuel shortage on the Gaza Strip, Palestinian electrical engineer Waseem Othman al-Khozendar invented in 2008 a way to convert his car to run on 32 electric batteries. According to al-Khozendar, the batteries can be charged with US$2 worth of electricity to drive from 180 to 240 km (110 to 150 mi). After a 7-hour charge, the car should also be able to run up to a speed of 100 km/h (60 mph).[126][127]

Japanese Professor Hiroshi Shimizu from Faculty of Environmental Information of the Keio University created an electric limousine: the Eliica (Electric Lithium-Ion Car) has eight wheels with electric 55 kW hub motors (8WD) with an output of 470 kW and zero emissions, a top speed of 370 km/h (230 mph), and a maximum range of 320 km (200 mi) provided by lithium-ion batteries.[128] However, current models cost approximately US$300,000, about one third of which is the cost of the batteries.

In 2008, several Chinese manufacturers began marketing lithium iron phosphate (LiFePO4) batteries directly to hobbyists and vehicle conversion shops. These batteries offered much better power to weight ratios allowing vehicle conversions to typically achieve 75 to 150 mi (120 to 240 km) per charge. Prices gradually declined to approximately US$350 per kW·h by mid 2009. As the LiFePO4 cells feature life ratings of 3,000 cycles, compared to typical lead acid battery ratings of 300 cycles, the life expectancy of LiFePO4 cells is around 10 years. This has led to a resurgence in the number of vehicles converted by individuals. LiFePO4 cells do require more expensive battery management and charging systems than lead acid batteries.[citation needed]

[edit]Currently available electric cars

Main article: Currently available electric cars

The Tesla Roadster is sold in the US and Europe and has a range of 245 miles per charge.

The REVAi, also known as the REVA G-Wiz iis available in several countries around the world.

The Th!nk City is sold in several European countries and production began in the U.S. in late 2010

Sales of the Mitsubishi i MiEV to the public began in Japan in April 2010, in Hong Kong in May 2010 and in Australia in July 2010.

The Nissan Leaf was introduced in December 2010 in Japan and the U.S.[129]

While as of 2010 there is no shortage of prototype, pre-production and concept electric cars only a few highway-capable models are currently on the market. These include the Tesla Roadster, Mitsubishi i MiEV, Th!nk City, and Nissan Leaf. The remainder of currently available electric cars are mostly low-speed, low-range neighborhood electric vehicles, electric city cars as well as some small-scale commercial conversion of internal-combustion based vehicles.

[edit]Government subsidy

See also: Tax incentives for PEVs by country

Several countries have established grants and tax credits for the purchase of new electric cars depending on battery size. The U.S. offers a federal income tax credit up to US$7,500,.[130] and several states have additional incentives.[131] The U.K. offers a purchase grant up to a maximum of GB£5,000 (US$7,600) beginning in January 2011.[132][133] As of April 2010, 15 European Union member states provide tax incentives for electrically chargeable vehicles, which consist of tax reductions and exemptions, as well as of bonus payments for buyers of PEVs and hybrid vehicles.[134][135]

[edit]Highway capable

Main article: List of production battery electric vehicles

See also: Cars planned for production and list of modern production plug-in electric vehicles

The following electric cars are currently in an advanced stage of development.

Selected list of future electric cars capable of at least 100 km/h (62 mph)

Model Top speed Acceleration Capacity

Adults+kids Charging time Nominal range Market release date

Wheego Whip LiFe 105 km/h (65 mph)

2

161 km (100 mi) Dec 2010

CODA Sedan 129 km/h (80 mph) 0–60 mi/h in 11 seconds

4

full charge in approx. 6 hours 193 km (120 mi) Q3 2011

REVA NXR 104 km/h (65 mph)

4

160 km (99 mi) 2011

Renault Fluence Z.E. 135 km/h (84 mph) 0-62 mph: 9.0 seconds (est)

5

6–8 hours with standard AC power; 30 minute rapid charge to 80% 161 km (100 mi) Early 2011

Tata Indica Vista EV 105 km/h (65 mph) 0-62 mph: 10.0 seconds (est)

4

241 km (150 mi) Q1 2011

DOK-ING XD Concept 130 km/h (81 mph) 0–100 km/h in 7.7 seconds

3

0-80% approx. 6 hours, 230 V/16A

0-100% approx. 8 hours, 230 V/16A

250 km (160 mi) 2011

Ford Focus BEV 137 km/h (85 mph)

5

approx 6 to 8 hours, 230 V/16A 160 km (99 mi) Late 2011

Hyundai BlueOn 130 km/h (81 mph) 0–100 km/h in 13.1

4

6 hours with 220 V power; 25 minute rapid charge to 80% 140 km (87 mi) Late 2012

Tesla Model S 193 km/h (120 mph) 0 to 97 km/h (0 to 60 mph) in 5.6 s

5+2

Full charge 3.5 hours using the High Power Connector or 45 minute QuickCharge 483 km (300 mi) 2012

The following pre-production models and plug-in conversions of existing models are currently undergoing field trials or are part of demonstration programs: Mini E, Smart ED, BYD e6, Audi A1 e-tron and Volvo C30 DRIVe Electric.

[edit]See also

Sustainable energy

Renewable energy

Anaerobic digestion

Hydroelectricity · Geothermal

Microgeneration · Solar

Tidal · Wave · Wind

Energy conservation

Cogeneration · Energy efficiency

Geothermal heat pump

Green building · Passive Solar

Sustainable transport

Plug-in hybrids · Electric vehicles

Environment Portal

v • d • e

Sustainable development portal

Wikimedia Commons has media related to: Electrically-powered automobiles

Compressed air car

Electric car use by country

Electric boat

Electric bus

Electric motorcycles and scooters

Electric vehicle conversion

Hybrid electric vehicle (HEV)

List of production battery electric vehicles

Plug-in electric vehicle (PEV)

Plug-in hybrid (PHEV)