Our glossary to help you understand the world of Electiric Vehicle charging.
‘Alternating current’ is an electric current in which the flow of electric charge periodically reverses direction, whereas in direct current (DC, see below), the flow of electric charge is only in one direction.
The SI unit for electric current.
A location, public or private, where electric vehicles can plug in and charge. There will be some arrangement of EVSE (See below) installed.
"Direct Current" is an electric current in which the flow of electric charge is in a constant direction, whereas in alternating current (AC, see above), the flow of electric charge periodically reverses direction.
Our EVSE Protocol Controller (EPC) is the intelligent part of our charging stations. It is the communication unit that talks to the car and enables charging in accordance with IEC 61851.
‘Electric Vehicle’ is any vehicle using an electric motor instead of solely an internal combustion engine (see below) for propulsion. This includes fully electrics, hybrids, plug-in hybrids and extended range electric vehicles.
‘Electric Vehicle Supply Equipment’ encompasses all the components and apparatuses installed and used for supplying electrical energy and necessary communications to an electric vehicle.
"Extended Range Electric Vehicle" - a vehicle that uses an electric motor for propulsion but also has an internal combustion engine onboard to provide power for a generator, which maintains a minimum charge level on the battery – as long as petrol in the tank is topped up, an E-REV has unlimited range. E-REVs can be plugged in and charged up, allowing an electric range of around 40 miles before the ICE fires up. Unlike a PHEV, E-REVs don't use the petrol/diesel engine to directly power the wheels.
Charging faster than what is capable through a standard domestic supply by using dedicated and appropriate EVSE (see above). Rated at about 7kW – 22kW as opposed to 3kW, allowing charging time of about 3 – 4 hours depending on battery capacity. Rapid Charge is quicker still (see below).
"Horsepower" - a unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second.
A type of electric vehicle that combines an internal combustion engine (ICE, see below) propulsion system with an electric motor propulsion system in order to increase the efficiency of the engine. The ICE maintains the battery charge; they cannot be plugged into an electricity supply. They offer better fuel economy than ICEs.
‘Internal Combustion Engine’ is an engine that burns fuels (typically fossil fuels) in a pressurised environment, turning chemical energy into mechanical energy. ‘ICE’ is often used to refer to any vehicle powered by an internal combustion engine.
"Kilowatt-hour" - a unit of energy equivalent to the energy transferred or expended in one hour by one kilowatt of power. Electric car battery size is measured in kilowatt-hours, so think of it as the electric car's equivalent of litres of fuel in a petrol tank.
‘kWh’ is a derived unit of energy equal to 3.6 megajoules. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.
Lead Acid Battery
A type of battery used in less modern electric cars. The energy density is much lower than that of lithium Ion batteries, which is the current standard. That means less power output and the need for more frequent charging. Lead acid batteries also have a shorter service life. They are, however, a lot cheaper than lithium ion batteries.
Lithium Ion Battery
These are the current standard in electric vehicle batteries, offering good energy density, power and fast charging ability. The life of a lithium Ion battery is estimated to be the same as the life of the car (eight to ten years). Of course 'end of life' here does not mean the cars or batteries won't work - after 10 years a lithium ion battery is expected to be at 80% efficiency, so they will still be usable - replacement will be a choice, not a requirement. Should you wish to replace your car's battery, it's possible they will still be in demand as storage devices for renewable energy in industry. They are expensive at the moment, but prices will reduce over time as more EVs hit the road.
"Nickel-Metal Hydride" - a type of battery used in some older electric vehicles, offering better energy density than lead acid but less than lithium ion.
‘Plug-in Hybrid Electric Vehicle’ is a form of hybrid electric vehicle (see above). It combines an ICE (See above) and batteries like that of the hybrid but has the capability of plugging into an external power source such as a charging station for charging the batteries.
Plug-in Car Grant
Plug-in car grant, which offers 25% off a new electric car’s list price up to £5,000.
An electric vehicle that is fully electric with no ICE (see above), using just batteries to power electric motors.
Photovoltaic Cells (PV)
Used on solar panels to convert radiation from the sun into electricity. Solar panels are becoming much more commonplace and can be installed at home to help charge electric cars, allowing true zero-emission motoring and a large cost saving over time. Even in the UK, users report it is possible to completely charge electric cars using solar power only. Feed-in Tariffs may also allow unused electricity to be supplied to the national grid, meaning you could earn money from installing a solar panel.
A four-wheeled vehicle with low power and of the same class as a moped or scooter. Electric quadricycles do not have the performance of the latest breed of electric cars and as they are not subject to the same stringent crash testing, safety is a concern. The Reva G-Wiz is an example of an electric quadricyle.
Rapid charging occurs only at dedicated locations and employs a 20-50kW current, allowing an 80% charge of a typical electric car in around 20-30 minutes. Some rapid chargers can top up the remaining 20% at a reduced rate in order to preserve the life of the battery. Regular rapid charging is not good for the long-term life of the battery, but does offer the chance to top up on the occasional longer journey.
The distance you can travel on pure electric power before the battery requires a recharge.
A term used to describe the fear of running out of battery while driving a pure electric car. Real-world accounts suggest range anxiety isn’t as common as thought, and trials show that anxiety recedes over time as drivers become more comfortable with their cars’ actual range capability.
An energy recovery system used in most electric vehicles that can help charge the battery while the car is slowing down. Typically the electric motor acts as the generator, so power can flow both ways between it and the battery. 'Regen' helps extend the range, while the process also help slow the vehicle in a similar way to engine braking in an ICE powered car.
"Revolutions Per Minute" - the number of times the shaft of an electric motor turns through 360 degrees in one minute.
International System of Units: a system of physical units.
Three-phase electric power
In an AC motor in an electric vehicle, three-phase current is used instead of single phase, as it generates a rotating magnetic field from zero RPM and is typically 150% more efficient in the same power range. In other words, high torque at zero revs is made possible by a three-phase system on an AC motor.
The twisting force that causes rotation. In the case of cars, torque rules and is the major factor in a car’s accelerative ability – with generous torque, the car’s throttle response is much sharper. Petrol and diesel engines deliver torque over a curve as RPM increases, meaning they have peak power at a given RPM. Electric motors, on the other hand, deliver maximum torque from zero revs, meaning acceleration from standstill can be phenomenal.
"Vehicle-to-Grid" - transferring electrical current from the battery of an electric car back into the National Grid while plugged in to the mains. V2G could help balance the grid in periods of high demand, alleviating the risk of power cuts.
"Well-to-Wheel" - measuring the CO2 emissions of a car, taking into account the production of the fuel or electricity. This is a fair analysis of the impact on the environment of electric vehicles, as they have zero emissions at point of use but clearly have an environmental impact earlier in the chain. However, for a fair comparison with an ICE vehicle, W2W must also be calculated in the drilling of the oil, refining and transportation, not just the tailpipe emissions. Taking this into account, an average electric vehicle will produce 80g/km of CO2 compared with 147-161g/km for an ICE (source: SMMT).