Electric car

                          Electric car

                          

          

 

 

·       an electric car (also battery electric car or all-electric car) is a plug-in electric automobile that is propelled by one or more electric motors, using energy typically stored in rechargeable batteries.

 

·       Since 2008, a renaissance in electric vehicle manufacturing occurred due to advances in batteries, concerns about increasing oil prices, and the desire to reduce greenhouse gas emissions.Several national and local governments have established tax credits, subsidies, and other incentives to promote the introduction and adoption in the mass market of new electric vehicles, often depending on battery size, their electric range and purchase price. The current maximum tax credit allowed by the US Government is US$7,500 per car. Compared with internal combustion engine vehicles, electric cars are quieter and have no tailpipe emissions, and, often lower emissions in general.

·       Charging an electric car can be done at a variety of charging stations, these charging stations can be installed in both houses and public areas.The two best selling electric cars, the Nissan Leaf and the Tesla Model S, have EPA-rated ranges reaching up to 151 mi (243 km) and 335 mi (539 km) respectively.

·       As of September 2018, there are over 4 million all-electric and plug-in hybrid cars in use around the world, of which, 2.6 million were pure electric cars (65%).The Nissan Leaf is the best-selling highway-capable electric car ever with 370,000 units sold globally, followed by the Tesla Model S with 253,000 units sold worldwide, both through October 2018.

 

 

1      Terminology

·       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 highway-capable automobiles powered by electricity. Low-speed electric vehicles, classified as neighborhood electric vehicles (NEVs) in the United States and as electric motorised quadricycles in Europe, are plug-in electric-powered microcars or city cars with limitations in terms of weight, power and maximum speed that are allowed to travel on public roads and city streets up to a certain posted speed limit, which varies by country.

·       While an electric car's power source is not explicitly an on-board battery, electric cars with motors powered by other energy sources are typically referred to by a different name. An electric car carrying solar panels to power it 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 battery electric vehicles, but may also refer to plug-in hybrid electric vehicles (PHEV).

 

2       Economics

 

2.1     Total cost of ownership

As of 2018, electric cars are less expensive to run than comparable internal combustion engine vehicles due to the lower cost of repairs and energy. However, as of 2018, electric cars on average cost significantly more to initially buy, and depreciate more quickly than conventional cars.

The Chinese auto manufacturer BYD calculated on its website in 2015 that a BYD e6 taxi over five years would give a saving of about $74,000 over the equivalent petrol consumption.

In 2018 the Australian Federal Government’s advisory firm on vehicle emissions estimated the TCO for electric cars was 5 to 10 thousand dollars more per year than a roughly equivalent petrol powered car.

2.2     Purchase cost

Several national and local governments have established incentives to reduce the purchasing price of electric cars and other plug-ins.

When designing an electric vehicle, manufacturers may find that for low production, converting existing platforms may be cheaper as development cost is lower, however, for higher production, a dedicated platform may be preferred to optimize design, and cost.

Almost 80% of electric vehicles in the U.S. are leased, while the lease rate for the country's entire fleet is about 30%.In early 2018, electric compact cars of 2014 are worth 23 percent of their original sticker price, as comparable cars with combustion engines worth 41 percent.

Batteries play a significant cost when designing an electric vehicle, for example; Tesla Motors uses batteries that cost around $200 per kilowatt hour.

2.3     Operating cost

According to a study done in 2018, the average operating cost of an electric vehicle in the United States is $485 per year, as opposed to an Internal combustion engines $1,117 per year.

 

 

3       Environmental aspects

·       Electric cars have several benefits over conventional internal combustion engine automobiles, including a significant reduction of local air pollution, as they do not directly emit pollutants such as particulates (soot), volatile organic compounds, hydrocarbons, carbon monoxide, ozone, lead, and various oxides of nitrogen.

·       Depending on the production process and the source of the electricity to charge the vehicle, emissions may be partly shifted from cities to the material transportation, production plants and generation plants. The amount of carbon dioxide emitted depends on the emissions of the electricity source, and the efficiency of the vehicle. For electricity from the grid, the emissions vary significantly depending on your region, the availability of renewable sources and the efficiency of the fossil fuel-based generation used.

·       The same is true of ICE vehicles. The sourcing of fossil fuels (oil well to tank) causes further damage and use of resources during the extraction and refinement processes, including high amounts of electricity.

·       In December 2014, Nissan announced that Leaf owners have accumulated together 1 billion kilometers (620 million miles) driven. This translates into saving 180 million kilograms of CO₂ emissions by driving an electric car in comparison to travelling with a gasoline-powered car. In December 2016, Nissan reported that Leaf owners worldwide achieved the milestone of 3 billion kilometers (1.9 billion miles) driven collectively through November 2016.

 

 

 

4       Performance

4.1     Acceleration and drivetrain design

·       Electric motors can provide high power-to-weight ratios, batteries can be designed to supply the currents needed to support these motors. Electric motors have flat torque curve down to zero speed. For simplicity and reliability, many electric cars use fixed-ratio gearboxes and have no clutch.

·       Many electric cars have motors that have high acceleration, relative to comparable cars, however, Neighborhood Electric Vehicles may have a low acceleration due to their relatively weak motors. This is largely due to the relatively constant torque of an electric motor, which often increase the acceleration relative to a similar motor power internal combustion engine.

·       Electric vehicles can also use a direct motor-to-wheel configuration which increases the available power. Having motors connected directly to each wheel allows the wheels to be used both for propulsion and as braking systems, thereby increasing traction. When not fitted with an axle, differential, or transmission, electric vehicles have less drive-train inertia.

·       For example, the Venturi Fetish delivers supercar acceleration despite a relatively modest 220 kW (300 hp), and top speed of around 160 km/h (100 mph). Some DC-motor-equipped drag racer EVs have simple two-speed manual transmissions to improve top speed. The Tesla Roadster (2008) 2.5 Sport can accelerate from 0 to 97 km/h (0 to 60 mph) in 3.7 seconds with a motor rated at 215 kW (288 hp). Tesla Model S P100D (Performance / 100kWh / 4-wheel drive) is capable of 2.28 seconds for 0–60 mph at a price of $140,000 [1]. As of May 2017, the P100D is the second fastest production car ever built, taking only 0.08 seconds longer for 0–97 km/h (0–60 mph), compared to a $847,975 Porsche 918 Spyder. The electric supercar Rimac Concept One can go from 0–97 km/h (0–60 mph) in 2.5 seconds.

 

5      Energy efficiency

·       Internal combustion engines have thermodynamic limits on efficiency, expressed as fraction of energy used to propel the vehicle compared to energy produced by burning fuel. 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 efficiency of 20%, while electric vehicles have on-board efficiency of over 90%, when counted against stored chemical energy, or around 80%, when counted against required energy to recharge.

·       Electric motors are more efficient than internal combustion engines in converting stored energy into driving a vehicle. Electric cars can not idle. Regenerative braking, which is most common in electric vehicles, can recover as much as one fifth of the energy normally lost during braking.

·       Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi). 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 (if the electricity is generated from natural gas) is 24.4 kW·h/100 km (0.39 kW·h/mi).

 

5.1     Cabin heating and cooling

·       While heating can be provided with an electric resistance heater, higher efficiency and integral cooling can be obtained with a reversible heat pump. PTC junction cooling is also attractive for its simplicity — this kind of system is used, for example, in the Tesla Roadster (2008).

·       To avoid using part of the battery's energy for heating and thus reducing the range, some models allow the cabin to be heated while the car is plugged in. For example, the Nissan Leaf, the Mitsubishi i-MiEV and the Tesla Model S can be pre-heated while the vehicle is plugged in.

·       Some electric cars, for example the Citroën Berlingo Electrique, use an auxiliary heating system (for example gasoline-fueled units manufactured by Webasto or Eberspächer) but sacrifice "green" and "Zero emissions" credentials. Cabin cooling can be augmented with solar power, or by automatically allowing outside air to flow through the car when parked. Two models of the 2010 Toyota Prius include this feature as an option. 

6       Controls

·       As of 2018, most Electric cars have similar driving controls to that of a car with a conventional automatic transmission. Even though the motor may be permanently connected to the wheels through a fixed-ratio gear and no parking pawl may be present the modes "P" and "N" are often still provided on the selector. In this case the motor is disabled in "N" and an electrically actuated hand brake provides the "P" mode.

·       In some cars the motor will spin slowly to provide a small amount of creep in "D", similar to a traditional automatic.

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, if it wasn't for regenerative braking which instead provides a more familiar response and recharges the battery to an extent. These features also reduce the use of the conventional brakes, significantly reducing wear and tear and maintenance costs as well as improving vehicle range.

 

 

7      Batteries

·       Lithium-based batteries are often chosen for their high power and energy density, although may wear out over a long period of time. However, there are many emerging technologies trying to combat this issue.

·       There are also other battery types, such as Nickel metal hydride (NiMH) batteries which have a poorer power to weight ratio than lithium ion, but are cheaper. Several other battery chemistries are in development such as zinc-air battery which could be much lighter.

7.1     Range

·       The range of an electric car depends on the number and type of batteries used, and as with all vehicles, the weight and type of vehicle, performance requirements, and the weather.

 

Comparison of EPA-rated range for model year 2016 and 2017 electric cars rated up until July 2017. Tesla vehicles shown correspond to the variants with the longest and shortest range for each model

·       The range of production electric vehicles in 2017 ranged from 100 kilometres (62 mi) (Renault Twizy) to 540 kilometres (340 mi) (Tesla Model S 100D)

·       The majority of electric cars are fitted with a display of expected range. This may take into account many factors of how the vehicle is being used, and what the battery is powering. However, since factors can vary over the route, the estimate can vary from the actual achieved range. The display allows the driver to make informed choices about driving speed and whether to stop at a charging point en route. Some roadside assistance organizations offer charge trucks to recharge electric cars in case of emergency.

·       A study in 2016 stated that 87% of US vehicle-days can be met by current affordable electric cars.

7.2      Charging  (Charging station)

·       Electric cars are typically charged overnight from a charging station installed in the owner's house, or from faster charging stations found in businesses and public areas.

·       An overnight charge of 8 hours will only give about a 40 mile charge with a standard 120 volt outlet whereas a 240 volt outlet would give around 180 miles in the same amount of time.

·       Within each major region of the world, electric car charging stations are essentially universal across car and charger brands, and simply plugging in a charger into an electric car will charge the car at the fastest rate that car and charger can support. A notable exception are the Tesla line of cars and charging stations, which use their own proprietary chargers. However, this can be solved by using a converter.

·       Some companies have been experimenting with battery swapping to eliminate delay while charging.

 

Panoramic view of Tesla supercharger rapid charging station in Tejon Ranch, California

BYD e6 is able to recharge in 15 Minutes to 80 percent

7.3     Hybrid vehicles

 

Further information: Hybrid vehicle

The BMW i3 has an optional gasoline-powered range extender engine

Some electric vehicles have built in generators, these are considered a type of hybrid vehicle.

 

7.4     Lifespan

Main article: rechargeable battery § Lifespan and cycle stability

As with all lithium-ion batteries, electric vehicle batteries may degrade over long periods of time, especially if they are frequently overcharged, however, this may take at least several years before being noticeable.

However, Nissan stated in 2015 that thus far only 0.01 percent of batteries had to be replaced because of failures or problems, and then only because of externally inflicted damage. The vehicles that had already covered more than 200,000 km (124,274 mi), have no problems with the battery.

7.5     Extraction

Over half of the world's cobalt, a key element in lithium-ion batteries, is mined in the Democratic Republic of Congo where the children are forced to mine the cobalt while having little to no protection.

 

 

7.6     Future

Autonomous park-and-charge

Volkswagen, in collaboration with six partners, is developing an EU research project that is focused on automating the parking and charging of electric vehicles. The objective of this project is to develop a smart car system that allows for autonomous driving in designated areas (e.g. valet parking, park and ride) and can offer advanced driver support in urban environments. Tesla has shown interest in making an arm that automatically charges their vehicles.

7.7     Lithium availability

 

 

The Salar de Uyuni in Bolivia is one of the largest known lithium reserves in the world

See also: rare-earth metals availability and supply security

It is estimated that there are sufficient lithium reserves to power 4 billion electric cars. Most electric cars use a lithium-ion battery and an electric motor which uses rare-earth elements. The demand for lithium, heavy metals, and other elements (such as neodymium, boron and cobalt) required for the batteries and powertrain is expected to grow significantly due to the future sales increase of plug-in electric vehicles in the mid and long term. Some of the largest world reserves of lithium and other rare metals are located in countries with strong resource nationalism, unstable governments or hostility to U.S. interests, raising concerns about the risk of replacing dependence on foreign oil with a new dependence on hostile countries to supply strategic materials.

7.8     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. 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).

7.9     Solar cars

Main article: Solar vehicle

Solar cars are electric vehicles powered completely or significantly by direct solar energy, usually, through photovoltaic (PV) cells contained in solar panels that convert the sun's energy directly into electric energy, usually used to charge a battery.

8      Safety

Side impact test of a Tesla Model X

 

                            

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.

8.1     Risk of fire

Main article: plug-in electric vehicle fire incidents

Like their internal combustion engine counterparts, electric vehicle batteries can catch fire after a crash or mechanical failure. Plug-in electric vehicle fire incidents have occurred, albeit less per mile than I.C.E vehicles. The first modern crash-related fire was reported in China in May 2012, after a high-speed car crashed into a BYD e6 taxi in Shenzhen.The second reported incident occurred in the United States on October 1, 2013, when a Tesla Model S caught fire over ten minutes after the electric car hit metal debris on a highway in Kent, Washington state, and the debris punctured one of 16 modules within the battery pack. A third reported fire occurred on October 18, 2013 in Merida, Mexico. In this case the vehicle was being driven at high speed through a roundabout and crashed through a wall and into a tree. The fire broke out several minutes after the driver exited the vehicle.

In the United States, General Motors ran in several cities a training program for firefighters and first responders to demonstrate how to safely disable the Chevrolet Volt’s powertrain and its 12 volt electrical system. The Volt's high-voltage system is designed to shut down automatically in the event of an airbag deployment, and to detect a loss of communication from an airbag control module. GM also made available an Emergency Response Guide for the 2011 Volt for use by emergency responders. The guide also describes methods of disabling the high voltage system and identifies cut zone information. Nissan also published a guide for first responders that details procedures for handling a damaged 2011 Leaf at the scene of an accident, including a manual high-voltage system shutdown, rather than the automatic process built-in the car's safety systems.

8.2     Vehicle safety

The weight of the batteries themselves usually makes an EV heavier than a comparable gasoline vehicle, 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 despite having a negative effect on the car's performance. Depending on where the battery is located, it may lower the center of gravity, increasing driving stability, lowering the risk of an accident through loss of control. 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.

Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires. The Insurance Institute for Highway Safety in America had condemned the use of low speed vehicles and "mini trucks," referred to as neighborhood electric vehicles (NEVs) when powered by electric motors, on public roads. Mindful of this, several companies (Tesla Motors, BMW, Uniti) have succeeded in keeping the body light, while making it very strong.

8.3     Hazard to pedestrians

See also: Electric vehicle warning sounds

At low speeds, electric cars produced less roadway noise than vehicles propelled by internal combustion engines. Blind or visually impaired people consider the noise of combustion engines a helpful aid while crossing streets, hence electric cars and hybrids could pose an unexpected hazard. 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), which affects all road users, not just 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.

The Government of Japan, the U.S. Congress, and the European Parliament passed legislation to regulate the 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. The Nissan Leaf was the first electric car to use Nissan's Vehicle Sound for Pedestrians system, which includes one sound for forward motion and another for reverse. As of January 2014, most of the hybrids and plug-in electric and hybrids available in the United States, Japan and Europe make warning noises using a speaker system. The Tesla Model S is one of the few electric cars without warning sounds; Tesla Motors will wait until regulations are enacted.Volkswagen and BMW also decided to only add artificial sounds to their electric drive cars only when required by regulation.

Several anti-noise and electric car advocates have opposed the introduction of artificial sounds as warning for pedestrians, as such an introduction is based on vehicle type and not actual noise level, a concern regarding ICE vehicles which themselves are becoming quieter.