An electric vehicle is a vehicle which uses electric motors to drive itself. EV is a shortened acronym for an electric vehicle. EV motors are powered from electric power. The electric power can be supplied to the motors in several ways. Motors can be powered (a) by the energy storage system (e.g. batteries) housed on the EV (b) by solar panels (c) by electricity generated by electric generator (placed on the EV) (d) through a collector system by electricity from off-vehicle sources.
EVs include electric trains, electric cars, electric bikes, electric scooters, electric buses, electric rickshaw, electric aircraft, etc.
Why need of Electric Vehicles?
With sustainable urbanization, economical personal mobility and security of energy in emphasis, there is a shift from the monopoly of Internal Combustion automobiles to alternative fuel vehicles.
Alternative fuels are vehicle fuels that are not composed of petroleum. Alcohols, Compressed Natural Gas (CNG), Electricity, Hydrogen, Liquefied natural gas (LNG), Liquefied petroleum gas (LPG) (also called propane), Liquids made from coal, Compressed Air, Liquid Nitrogen, and Biodiesel are some alternative fuels.
Electricity is the only fuel that can economically replace petroleum products as the main source of fuel as it is easier to mass-produce on a scale to satisfy the global population.
They boost energy security, improve fuel economy, lower fuel costs, and reduce emissions because they employ electric-drive technologies. However, the drawbacks faced are frequent and long charging time, non-availability of charging stations and range anxiety.
Electric Vehicle History
In 1908, Aero vironment first came up with an idea of Electric Vehicle for General Motors. Then, General Motors converted this invention from the prototype to the production class that was marketed in 1996 and 1999. After that Electric Vehicle came into existence.
Types of Electric Vehicle
Electric Vehicles mainly are of four types classed by the degree that electricity is used as their energy source.
- Battery Electric Vehicle
- Plug-in Hybrid Electric Vehicle
- Hybrid Electric Vehicle
- Fuel-cell Electric Vehicle
a). Battery Electric Vehicle (BEVs) or Plug-in Electric Vehicles (PEVs)
- These vehicles run entirely on an electric drive train and battery, without a conventional internal combustion engine.
- These vehicles take an external source of electricity to recharge their batteries by plugging into a power grid.
- BEVs may employ regenerative braking to recharge their batteries.
- Examples: BMW i3, Chevy Bolt, Chevy Spark, Nissan LEAF, Ford Focus Electric, Hyundai Ioniq, Mitsubishi i-MiEV, Tesla Model S, Tesla X, Tesla Model 3, Toyota Rav4, Volkswagen e-Golf.
b). Plug-in Hybrid Electric Vehicles (PHEVs)
- These vehicles run mostly on batteries that are recharged by plugging into the power grid.
- These vehicles are equipped with an internal combustion engine that can recharge the battery and/or replace the electric drivetrain with gasoline propulsion system when the battery is low or more power is required.
- Examples: Mercedes C350e, Fiat 500e, Hyundai Sonata, Kia Optima, Porsche Cayenne S E-Hybrid, Porsche Panamera S E-hybrid, Toyota Prius, Volvo XC90 T8, Mercedes S550e, Mercedes GLE550e, Mini Cooper SE Countryman, Audi A3 E-Tron, BMW 330e, BMW i8, Chevy Volt, Chrysler Pacifica, Ford C-Max Energi, Ford Fusion Energi.
c). Hybrid Electric Vehicles (HEVs)
- These vehicles have two complementary drive systems: an electric motor with battery and a gasoline engine with a fuel tank.
- The engine and the motor can simultaneously turn the transmission, which powers the wheels.
- It is noted that HEVs cannot be recharged from the power grid directly. HEVs energy comes entirely from gasoline.
- Examples: Toyota Prius Hybrid, Honda Civic Hybrid, Toyota Camry Hybrid
d). Fuel-cell Electric Vehicles
- Instead of storing and releasing energy like a battery, fuel-cell electric vehicles create electricity from hydrogen and oxygen.
- However, fuel-cell technology is not yet problem free. Extracting hydrogen from a water molecule is an energy-intensive process that generates greenhouse gas emissions if renewable energies are not used.
- Example: Tucson Fuel Cell | A Hydrogen Fuel Cell Car
Comparison between Plug-in and Plug-in Hybrid Electric Vehicles
|Plug-in Electric Vehicles||Plug-in Hybrid Electric Vehicles|
|Propulsion||Electric motor/battery only||Electric motor/battery plus gasoline engine|
|Refueling||Recharge with electricity||Recharge with electricity or refuel with gasoline|
|Range||70 – 100 miles on a full charge||15 – 35 miles on battery power alone, and 300+ in electric-gasoline hybrid mode|
|Charging time||4-6 hours to fully charge using a 220-volt charger.||About 1 hour to fully charge using a 220-volt charger, and about 3 hours at 120-volts.|
|Battery||Lithium-ion battery size
24kWh – 36 kWh
|Lithium-ion battery size is smaller than those found in pure PEVs.|
Electric Vehicle Charging stations
Electric vehicle charging stations are of two types, onboard stations and off-board stations.
The onboard is fitted in the vehicle while offboard is placed at some specific location to create commercial charging stations.
Electric Vehicle Charging Standards
The following are the standards that are used in developing a charging station.
- International Electrotechnical Commission (IEC)
- Institute of Electrical and Electronic Engineers Standards Association (IEEE-SA)
- Society of Automotive Engineers (SAE) of United States
- GuoBiao (GB) of China
- Japan Electric Vehicle Standard (JEVS) of Japan
1. International Electrotechnical Commission
The International Electrotechnical Commission is a well-known international standards organization that prepares and publishes International Standards in electrical, electronic and related technologies.
2. Institute of Electrical and Electronics Engineers Standards Association
The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) is an organization which is a part of IEEE that develops global standards for a wide range of industries, including health, power, and energy, robotics, telecommunications, transportation, etc.
3. SAE International
SAE International, known as the Society of Automotive Engineers, is a U.S.-based, standards organization for engineering professionals in various industries. Their principal emphasis is placed on transport industries such as aerospace, automotive, and commercial vehicles.
4. GB standards
GB standards are the Chinese national standards issued by the Standardization Administration of China (SAC), the Chinese National Committee of the ISO and IEC. GB stands for “Guobiao”. The Mandatory standards are prefixed as “GB”. The Recommended standards are prefixed as “GB/T”. A standard number follows “GB” or “GB/T”.
5. Japan Electric Vehicle Standard (JEVS)
Japan Electric Vehicle Standard (JEVS) are the standards of Japan. CHAdeMO charger follows the JEVS. CHAdeMO was formed by The Tokyo Electric Power Company, Mitsubishi, Nissan, and Fuji Heavy Industries.
Charging Levels of Electric Vehicle Charger
To charge the batteries, EVs are connected to the electric grid, which provides different connection options called “charging levels”.
At present standard, SAE J1772 defines six charging levels as AC Level I, AC Level II, AC Level III. AC Level III and DC charging are termed as fast charging. The only standards that currently set out specifications for fast charging are “JEVS” and “SAE J1772 Combo”. In parallel, Tesla has developed its own DC fast-charge system, “Tesla Supercharger”. Level I operates at 120 V AC while Level II uses 208 or 240 V AC and fast charging requires 200 to 450 V DC.
The following Table-1 shows the different charging levels configuration that is certified by SAE standards.
|Charging Levels||Specification Details|
|AC Level I (SAE J1772)||120V, 1.4 kW (12 A)
120V, 1.9 kW (16 A)
|AC Level II (SAE J1772)||240 V, up to 182 kW (80 A)|
|AC Level III||480 V, 20 kW (150A) Single-phase and Three-phase|
|DC Level I||200-450 V DC, up to 36 kW (80 A)|
|DC Level II||200-450 V DC, up to 90 kW (200 A)|
|DC Level III||200-600V DC (proposed) up to 240 kW (400 A)|
Comparison between Different Charging Levels
The following Table-2 compares the three charging levels: Level I, Level II, Level III. It provides a detailed specification of the different levels of charging available in the world. From this, Level I is suitable for residential charging while Level III is suitable for commercial charging. Level I takes maximum charging duration whereas, Level III or fast charging takes the least duration. Hence, fast charging is preferred.
|Charging Level I||Charging Level II||Charging Level III|
|Charging Outlet||120 V||240 V||480V|
|Maximum Power Rating||2 kW||2- 20 kW (3.5 kW relevant for home charging)||20-50 kW|
|Time is taken to charge batteries completely||PHEV
7 to 10 hours
17 to 22 hours
3 to 4 hours
less than half an hour
|Charging Speed||Slowest of charging levels||Moderate of charging levels||Fastest of charging levels|
|Relevant for home charging||Relevant for home charging (3.5 kW) and commercial charging (20 kW)||Relevant for Commercial charging|
|Power Supply||Single-phase Supply||Single-phase Supply||Three-phase Supply|
Challenges with Electric Vehicle
Charging stations for Electric Vehicles need to be developed and made accessible the way petrol pumps are for conventional automobiles. There are two modes of charging, residential and commercial. Commercial charging deploys fast AC charging and fast DC charging. Fast AC is a salubrious option over fast DC because it is easily available from the grid and can be transmitted easily over long distances.
Issues Related to the Charging of Electric Vehicles
Using the slowest charging level, PHEVs and PEVs double the load of a typical home (2 kW).
Suppose that a distribution transformer serves 7-8 homes, so any significant load increase as represented by PHEVs and PEVs will translate into a significant relative load increase for transformers that are not designed to accommodate such increase.
The proposed solution to this problem is to charge EVs at night when the home load is at its minimum.
Another solution is to rapidly charge an EV at night using stored power that is generated by the PV modules during the day. With this approach, the extra power consumption of the car is not being presented to the grid.
Another issue is regarding control, i.e., “when to charge an electric car”.
For this, there must exist a communication and information exchange between the grid and the Electric Vehicle charging hardware.
The proposed solution is to provide a bi-directional flow of information and control actions in conventional power grids which are known as smart grids.
Smart meters that are connected at consumer end play an important role in the smart grid. The smart meters transmit energy consumption information at a grid connection point back to the utility so as to control demand levels based on various mechanisms, such as through differentiated pricing that motivates users to charge their EVs at night. In extreme cases, the control signal may directly disconnect the Electric Vehicle charging circuit until load levels are reduced.
The third issue is regarding charging time.
AC Level 1 charges the EV in about 10-11 hours and AC level 3 charges the EV in 5-7 hours. These charging levels are available for home charging. So there is a need for a fast charger that will reduce the charging time.
The fourth issue is regarding range anxiety.
As in India, there is no commercial charging station available like petrol pumps, so there is range anxiety among people. A solution to this problem is to have a well-connected network of fast charging station like we have petrol pumps so that people can have easy access to charging their vehicles on the go.
Electric vehicle battery
An electric vehicle battery is one of the key elements of any electric vehicle. In this article, we provide detailed information on types of battery for electric vehicles and their advantages and disadvantages for consumers who want to understand this element more fully.
A battery is an electrochemical energy storage device that can release an electrical charge when needed. It generally consists of an anode, a cathode and an electrolyte (separator). Different battery types are typically identified by the materials that make up one or more of those components (e.g., lead-acid).
Batteries may be made up of one or more cells, which can be connected (in series) to provide a higher voltage. For example, a typical 12-volt car battery is made up of six cells connected internally, while a battery pack for a battery electric vehicle (BEV) may have hundreds of individual cells. Battery characteristics that are particularly important for automotive use include their energy density and power density.
Energy density is a measure of how much energy a battery can hold. The higher the energy density, the longer it will last before needing to be recharged.
Power is the rate at which energy is used. Power density is a measure of how much power a battery can deliver on-demand; that is, how quickly it can release its energy (and conversely, how quickly it can be recharged).
Different types of Electric vehicle battery
Here are some common types of commercial automotive batteries and some of their characteristics and advantages.
Lead-acid batteries are used in conventional cars and trucks for starting, ignition, lighting and other electrical functions.
They are relatively inexpensive and have a high power density but a relatively low energy density.
Nickel-Metal Hydride (Ni-MH) batteries are commonly used in today’s hybrid vehicles, and in low-cost consumer applications, such as electric razors, toothbrushes, cameras, and camcorders.
Their cost is moderate and they have an energy density about twice that of lead-acid batteries. However, their power density is lower in terms of volume (space required).
They also have a higher self-discharge rate and so tend to discharge when left unused. Although they are capable of delivering rapid power bursts, repeated rapid discharges with high loads reduce the battery’s cycle life.
Consequently, they are better suited to hybrid applications than BEVs, which typically experience deep discharge cycles.
3. Lithium-ion (Li-ion)
Lithium-ion batteries are commonly used in cell phones and laptop computers and they are becoming the battery of choice for plug-in hybrids and BEVs, as well as some conventional hybrids.
Their energy density and power density are both typically several times those of lead-acid and NiMH batteries and their charge/discharge efficiency are also higher.
They are, however, more expensive and in their most common form, their temperature must be well controlled, sometimes necessitating an elaborate and costly battery cooling system in the vehicle.
Because of their high energy density, lithium-ion batteries are the preferred choice for many plug-in hybrids and BEVs either currently or soon to be available.
4. Lithium Polymer (Li-poly)
The lithium-polymer battery is similar to other lithium-ion batteries except it uses a solid plastic (polymer) electrolyte. This means its cell shape is not restricted to the cylindrical form of most others and can be altered to conform to specific spaces within a vehicle, thus making better use of space.
Its other characteristics are similar to those of other Li‑ion batteries. Li-poly batteries are already being used in some hybrid vehicles.
5. Lithium Iron Phosphate (LFP)
There are several Lithium-ion battery variants. These variants change according to internal chemistry, specifically the material used in the battery’s cathode. The most common cathode materials are cobalt oxides and manganese oxides.
The Lithium iron phosphate battery uses lithium-ion chemistry but with an iron phosphate cathode. (F is the chemical symbol for iron, thus LFP). Compared to other Lithium-ion batteries, it offers superior heat and chemical stability with no risk of fire in the event of an overcharge or short circuit.
It also typically has a higher peak-power rating, but its energy density is significantly lower than in other Lithium-based batteries.
Lithium iron phosphate batteries are now being used in hybrids and BEVs by some automakers, who consider that their safety and power advantages outweigh their lower energy density.