In
the United States, General Motors (GM) ran in several cities a training program
for firefighters and first responders to demonstrate the sequence of tasks
required to safely disable the Chevrolet Volt’s powertrain and its 12 volt
electrical system, which controls its high-voltage components, and then proceed
to extricate injured occupants. 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.
Great effort is taken to keep the mass of an
electric vehicle as low as possible to improve its range and endurance.
However, the weight and bulk of the batteries themselves usually makes an EV
heavier than a comparable gasoline vehicle, reducing range and leading to
longer braking distances; it also has less interior space. 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 despite having a negative effect on
the car's performance. 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. In a single car accident 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. Many electric cars have a small, light and fragile body,
though, and therefore offer inadequate safety protection. 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.
At
low speeds, electric cars produced less roadway noise as compared to vehicles
propelled by internal combustion engines. 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. 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.
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 March 2013, most of the hybrids
and plug-in electric cars available in the United States make warning noises
using a speaker system. The Tesla Model S is one of the few electric-drive cars
without warning sounds, because Tesla Motors is awaiting the National Highway
Traffic Safety Administration final rule.
Far
and away, the largest concern for electric vehicles is their batteries. The
limitations of range, availability of charging, safety, lifespan, cost of
replacement are just some of the things considered regarding batteries. 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. 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.
Unlike
vehicles powered by fossil fuels, BEVs are most commonly and conveniently
charged from the power grid overnight at home, without the inconvenience of
having to go to a filling station. Charging can also be done using a street or
shop charging station. The electricity
on the grid is in turn generated from a variety of sources; such as coal, hydroelectricity,
nuclear and others. Power sources 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.
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 as the charging interface for electric
vehicles in California in June 2001. In Europe the ACEA has decided to use the
Type 2 connector from the range of IEC_62196 plug types for conductive charging
of electric vehicles in the European Union as the Type 1 connector (SAE
J1772-2009) does not provide for three-phase charging. 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.
Reports
emerged in late July 2013 of a significant conflict between the companies
responsible for the two types of charging machines. The Japanese-developed
CHAdeMO standard is favored by Nissan, Mitsubishi, and Toyota, while the
Society of Automotive Engineers’ (SAE) International J1772 Combo standard is
backed by GM, Ford, Volkswagen, and BMW. Both are direct-current quick-charging
systems designed to charge the battery of an electric vehicle to 80 percent in
approximately 20 minutes, but the two systems are completely incompatible. In
light of an ongoing feud between the two companies, experts in the field warned
that the momentum of the electric vehicle market would be severely affected.
Richard Martin, editorial director for clean technology marketing and
consultant firm Navigant Research, stated:
“Fast
charging, however and whenever it gets built out, is going to be key for the
development of a mainstream market for plug-in electric vehicles. The broader
conflict between the CHAdeMO and SAE Combo connectors, we see that as a
hindrance to the market over the next several years that needs to be worked
out. Newer cars and prototypes are looking at ways of dramatically reducing the
charging times for electric cars. The BMW i3 for example, can charge 0-80% of
the battery in under 30 minutes in rapid charging mode.”
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—although, 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 and the Tesla Roadster can accept up to 16.8 kW (240V
at 70A) from the High Power Wall Connector. 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.
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). Using regenerative
braking, a feature, which is present on many hybrid electric vehicles,
approximately 20 percent of the energy usually lost in the brakes, is recovered
to recharge the batteries.
An
alternative to quick recharging is to exchange a discharged battery or battery
pack for a fully charged one, saving the delay of waiting for the vehicle's
battery to charge. Battery swapping is common in warehouses using electric
forklift trucks. The concept of exchangeable battery
service was first proposed as early as 1896 in order to overcome the limited
operating range of electric cars and trucks. The concept was first put into
practice by Hartford Electric Light Company through the GeVeCo battery service
and was initially available for electric trucks. Both vehicles and batteries
were modified to facilitate a fast battery exchange. The service was provided
between 1910 and 1924 and during that period covered more than 6 million miles.
A rapid battery replacement system was implemented to keep running 50 electric
buses at the 2008 Summer Olympics.
Tesla
Motors designed its Model S to allow fast battery swapping. In June 2013, Tesla
announced their goal to deploy a battery swapping station in each of its
supercharging stations. At a demonstration
event, Tesla showed that a battery swap operation with the Model S takes just
over 90-seconds, about half the time it takes to refill a gasoline-powered
car. The first stations will be deployed
along Interstate 5 in California where, according to Tesla, a large number of
Model S sedans make the San Francisco-Los Angeles trip regularly. The Washington, DC to Boston corridor, will
follow these stations. Each swapping station will cost $500,000 USD and will
have about 50 batteries available without requiring reservations. The service
would be offered for the price of about 15 US gallons (57 l;
12 imp gal) of gasoline at the current local rate, around $60 to $80
USD at June 2013 prices.
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, optimal level. Lithium-ion batteries degrade faster when
stored at higher temperatures.
The
future of battery electric vehicles depends primarily upon the cost and
availability of batteries with high specific energy, power density, 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.
Diarmuid O'Connell, VP of Business Development at Tesla Motors, estimates that
by the year 2020 30 percent of the cars driving on the road will be battery
electric or plug-in hybrid.
Nissan
CEO Carlos Ghosn has predicted that one in 10 cars globally will run on battery
power alone by 2020. 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.
It is estimated that there are sufficient lithium reserves to power four
billion electric cars.
As
of November 2013, the number of mass production highway-capable all-electric
passenger cars and utility vans available in the market is limited to about 25
models. Most electric vehicles in the world roads are low-speed, low-range
neighborhood electric vehicles (NEVs) or electric quadricycles. Pike Research
estimated there were almost 479,000 NEVs on the world roads in 2011. The two
largest NEV markets in 2011 were the United States, with 14,737 units sold, and
France, with 2,231 units. The Renault Twizy all-electric heavy quadricycle,
launched in Europe in March 2012 and with global sales of 9,020 units through December
2012, became the best selling plug-in electric vehicle in Europe for 2012. The
top selling markets were Germany with 2,413 units, France with 2,232 units, and
Italy with 1,545 units sold in 2012. As of November 2013, global Twizy sales
totaled 11,879 units.
The
world's top selling highway-capable electric car ever is the Nissan Leaf,
released in December 2010, with global sales of over 92,000 units delivered by
early December 2013. All-electric models scheduled for market launch in 2014
include the Volkswagen e-Golf, Mercedes-Benz B-Class Electric Drive,
Mercedes-Benz SLS AMG Electric Drive, Tesla Model X, and the limited production
Detroit Electric SP.01.
As
of September 2013, over 60,000 all-electric cars have been sold in the U.S.
since 2008, led by the Nissan Leaf, with 35,588 units, followed by the Tesla
Model S with 16,251 units, and the Ford Focus Electric with 2,028 units sold
through September 2013. Accounting for plug-in hybrid electric cars sold since
2010 (about 80,000), the United States has the largest fleet of plug-in
electric vehicles (PEVs) in the world, with over 140,000 highway-capable
plug-in electric cars sold through September 2013. A total of 17,800 plug-in
electric cars were delivered during 2011, more than 53,000 during 2012, and
over 67,700 units during the first nine months of 2013. PEV sales during the
first nine months of 2013 represented a 0.58 percent market share of total new
car sales, up from of 0.37 percent in 2012, and 0.14 percent in 2011.
The
Chevrolet Volt is the top selling plug-in hybrid, with 48,218 units, followed
by the Toyota Prius Plug-in Hybrid with 20,724 units, and the Ford C-Max Energi
with 6,668 units sold through September 2013. During the first nine months of
2013 sales were led by the Chevrolet Volt with 16,760 units, followed by the
Nissan Leaf with 16,076 cars, and the Tesla Model S with about 13,500 units.
August 2013 is the best month on record for U.S. plug-in vehicle sales, with
more than 11,000 units delivered, representing a market share of 0.76 percent
of new car sales.
California,
the largest United States car market, is also the leading plug-in
electric-drive market in the country. About 40 percent of the segment's
nationwide sales during 2011 and 2012 were made in California, while the state
represents about 10 percent of all new car sales in the country. From January to May 2013, 52 percent of
American plug-in electric car registrations were concentrated in five
metropolitan areas: San Francisco, Los Angeles, Seattle, New York and Atlanta.
During 2011, all-electric cars (10,064 sold)
oversold plug-in hybrids (7,671 sold), but increased Volt sales, together with
the introduction of the Prius PHV and the Ford C-Max Energi, allowed plug-in
hybrids to take the lead over pure electric cars during 2012, with 38,584 PHEVs
sold versus 14,251 BEVs. During the first nine monts of 2013, sales of pure
electric cars (35,261) outsold plug-in hybrids (32,718), due to large sales of
the Tesla Model S and Nissan Leaf during 2013. During the first half of 2013,
all-electric vehicle sales also outsold plug-in hybrids in California. During
this period a total of 15,444 new plug-in electric vehicles were sold in the
state, with plug-in hybrids representing a market share of 0.7 percent of new
vehicle sales, while battery electric vehicle market share was 1.1 percent.
Hopefully,
this wealth of information on hybrid and full electric vehicles will help you
make your decision if one of these vehicles is in your future. We will also
look at diesel engine vehicles, as there have been a lot of advancements in
diesel technology and new model introductions in recent years.
