While they’ve become a common sight on our roads, there are still many rumours, half-truths and misinformation making the rounds about EVs. With our comprehensive glossary, we define the most important terms you need to improve your EV literacy. If nothing else, you can use it to impress your friends at the bar!
Talking about the refuelling process in a buyer’s guide on diesel vans wouldn’t make sense, let alone function as a criterion for or against the purchase of a particular model. It’s different with EVs. EV buyer’s guides seem to be about nothing other than range, charging power, charging stations, and charging logistics… but modern, electric vehicles offer many advantages over traditional combustion engines. And it’s not about the environment – an EV does harm, too. Environmental protection requires new, more sustainable concepts than individual mobility. But electric cars are a step in the right direction: locally emissions-free, lower energy consumption during driving, and a completely new driving experience. Even underpowered EVs can easily drop most of the larger combustion vehicles in the city. You also get added comforts like heating or cooling in the interior via an app before you get in, on-board entertainment, or even a high-power 230 volt socket for a mobile party.
Finally, electric cars also force you to slow down and take regular breaks as they need to be recharged, improving safety and well-being on long hauls. We’ve compiled this comprehensive glossary of technical terms and easily understandable definitions surrounding EVs so that you can impress your buddies at the bar or wax lyrical about their pros and cons to friends and family. Together with our interactive buyer’s guide, it could also help you when chatting to dealers and figuring out which should be your first BEV. Say whaaat? No worries, it’s just one of the technical terms we cover in this glossary (see EV). But that’s enough talk, let’s dive right in – in alphabetical order, of course!
AC/DC: No, we’re not talking about the rock band, but about the electric currents flowing through your EV and making it go. AC refers to an alternating current, which is what you’ll find in every household. DC stands for direct current, such as you get from batteries. You can use either to charge an electric car. At home and at slow charging stations, you’ll be charging via AC. In that case, the current must be converted to DC before going into the battery since batteries can only accept direct currents. Doing so results in conversion losses. Charging with an alternating current is quite slow, too, capable of drawing just 2.3 to 43 kW. DC, on the other hand, can charge the battery directly. The fastest charging stations currently reach up to 350 kW.
Asynchronous motor (ASM): There are two basic ways electric motors can work. In the case of the asynchronous motor, the rotor follows the stator’s rotating magnetic field with a short delay (asynchronously) since the rotor and stator are not poled exactly the same (synchronous). In a synchronous motor, the rotor’s and the stator’s magnetic field rotate synchronously – as the name suggests. An asynchronous motor is comparatively simple in design and thus less expensive to produce than synchronous motors. However, it’s heavier and less efficient.
Autonomous driving: This simply refers to the ability of a car to drive on its own. The degree of autonomy is categorised into 6 levels (0–5), which the international standardisation organisation refers to as SAE-ISO J3016. Level 0 means zero autonomy, where the drivers must do everything themselves. Fully autonomous driving, level 5, only requires the system to be switched on and a destination to be entered. No driver needed. Levels 1 and 2 refer to assisted driving and level 3 goes into limited automation. You can only refer to it as autonomous driving from level 4. Automated driving according to level 3 has been legally regulated and permitted in Germany since 2017. In that case, the car briefly controls all the tasks required for driving while the driver monitors it and intervenes at regular, relatively short intervals, as requested by the vehicle.
Bidirectional charging: In this case, the car battery isn’t just used to power the motor but can also supply energy to other electronic devices, ideally even supplying your home with electricity. In the future, EVs with the capability of bidirectional charging will be an important part of the envisioned Smart Grid, where EV batteries can be used to optimise the electricity grid by acting as a huge network of decentralised storage devices. Particularly in the case of renewable energies, there are big fluctuations in the amount of power generated, depending on the time of day and weather, which we must currently compensate for with fossil fuelled power plants. In the future, electricity providers could store excess energy in EV batteries and then use it to supply households when there’s little being generated. However, this won’t happen without significant investments – both from the network operators and private households. You will need a new home EV charger, at least.
BMS: Refers to the Battery Management System, which should be included in every battery-powered device. The BMS controls and monitors the battery, as well as the charging and discharging processes. If necessary, it limits the battery performance when it’s running low or very cold, for example. It is also responsible for balancing the individual cells. Their voltages naturally drift apart during use, and the potential energy that can be drawn always depends on the weakest cell. By balancing them, all cells are brought back to the required nominal voltage.
CCS: The combined charging system is the predominant charging technology for EVs in Europe and is now the accepted standard. The system combines fast and slow charging in one socket. For charging with an alternating current, you only need the upper part of the socket for the type 2 plug. For quick charging at corresponding DC charging stations, there’s an additional and significantly larger plug for the two DC poles below the type 2 socket. CCS 2.0 allows charging currents of up to 350 kW.
CHAdeMo: At least in Europe, CHAdeMo is a threatened genus. This Japanese rapid-charging technology has been pushed further to the brink in Germany since standardising CCS. Theoretically, CHAdeMO already allows charging currents of up to 500 kW. The name is an abbreviation of “CHArge de MOve” or “charge for moving” and is derived from the Japanese phrase “o cha demo ikaga desuka” Translated to English, this means “how about a cup of tea?”, referring to the time it would take to charge a car.
Charging point: A charging point refers to an individual power outlet from which you can charge your EV. For example, if a charging station has one CCS and one type 2 outlet, it provides two charging points.
Charging station: A permanently installed, usually publicly accessible charging facility for electric cars. Many charging stations provide more than one charging point. In European cities, you will usually find charging stations with two socket types capable of providing 11 kW each, often supplemented by a standard power outlet. This can be used for electric bicycles or as an emergency solution if all the type 2 points are occupied.
C-rate: This value defines the power consumption or charging current ratio to the nominal battery capacity. For example, if a 70 kWh battery delivers up to 280 kW of power, the C-rate is 4. With a constant power output or input of 70 kW, this battery would be depleted or fully charged in one hour. That’s referred to as 1C. In current EVs, the charging C-rate is typically between 1C and about 4C. While discharging, the C-rate can go briefly up to 7C or more.
DC: see AC/DC
Degradation: A battery ages, that is, it loses more and more of its original capacity as time goes on. This applies equally to notebooks, smartphones and ebikes as it does to the much larger EV batteries. Ageing is inevitable. However, the degree of ageing depends on many factors. In addition to the actual age of a battery, the type of power consumption, temperature, and state of charge play a major role. High currents, low temperatures and extremely high or low states of charge are poison for (almost) every battery.
DoD: An acronym for a battery depth of discharge. DoD is the exact opposite of the state of charge (SoC), so that DoD and SoC always add up to 100%.
EV: EV is the generic term for electric-powered cars, short for electric vehicle. For a more detailed specification of the type of EV, the term is further subdivided into:
- BEV: This acronym is mainly used in English-speaking countries when referring to an electric vehicle. It’s short for battery electric vehicle. As such, hybrids can’t be categorised as BEVs.
- FCEV: Short for fuel cell electric vehicle. In this case, the motor doesn’t draw power from a battery, but rather from a fuel cell, which generates electricity by combining hydrogen and oxygen. The only local byproduct you’re left with is water. However, the production of hydrogen is extremely energy-intensive, which is still largely derived from fossil fuels.
- HEV: An acronym for hybrid electric vehicle. HEV refers to a vehicle with an internal combustion engine and an electric motor. However, the HEV designation doesn’t tell us anything about the type of hybrid system. For example, a mild hybrid electric vehicle only supports the internal combustion engine to increase its efficiency and provide regenerative braking. A full hybrid, on the other hand, can rely solely on the electric motor, momentarily.
- PHEV: The relatively young plug-in hybrid genus (plug-in hybrid electric vehicle) is always based on a full hybrid system. Therefore, these cars can also drive without the support of the internal combustion engine, but a full charge usually gives you a range of just 40 to 70 km. In contrast to a standard full HEV, however, a PHEV can be plugged into a socket or home EV charger to recharge.
Fast charger: As a rule, a fast charger is capable of putting out at least 50 kW via direct current. Earlier models of the Renault Zoe were able to charge at 43 kW using alternating current. It’s up for debate whether this can be referred to as fast charging.
Gross capacity: This is the maximum energy content of a rechargeable battery. However, to increase the battery service life, the amount you can use is limited in most cases (see net capacity), ranging from 80–90%. The battery management system (see BMS) controls the release of the net capacity in accordance with a wide range of variables. In addition, it prevents deep discharging or overcharging. Both instances would damage the battery disproportionately. A deep discharge usually results in a technical defect.
Home EV charger: In principle, every electric car can be charged from a household socket. However, due to the extremely long charging times and them not being designed for continuous loads, installing a home EV charging station is highly recommended. Also, because the charging losses are significantly lower with an EV charger than with a standard socket. It’s a kind of private charging station, which is usually supplied with three-phase current. Depending on the current, the charging power of a home EV charger is between 11 and 22 kW, though models that put out more than 11 kW are subject to approval. The plugs and cables of a home EV charging point are designed to withstand high and continuous loads. Modern devices also offer smart features such as automated charging with excess PV power.
HPC: High power charger – the fastest public charging stations currently out there. HPC chargers provide a charging current ranging from 100 to 350 kW. The HPC network relies exclusively on the CCS standard for charging electric vehicles and is supplied by a wide variety of manufacturers and operators.
kW: Short for kilowatt, this refers to the electrical power, which is a product of voltage and amps. In the case of electric cars, it’s used to refer to both the output of the motor and the charging current. Of course, you can also convert kilowatt to horsepower, which is typically used to refer to the power produced by internal combustion engines: 1 kW = 1.36 hp (metric).
kWh: In contrast to the power (kW), a kilowatt hour (kWh) refers to the work done in one hour. Simply put, if 1 kW is provided for one hour, this corresponds to 1 kWh of electrical work. Generally speaking, the capacity of an EV battery is given in kWh. The correct expression, however, is energy content.
Net capacity: The usable capacity for powering the motor is referred to as the battery’s net capacity. This is less than the gross capacity in order to avoid extreme states such as a deep discharge or overcharging. Caution: some manufacturers still state the gross capacity in the technical data sheets, which may well be 10 percent above the usable, i.e. net capacity.
One-pedal driving: Since an electric motor is technically the same as a generator, it’s capable of doing more than just driving the wheels. If no external energy is supplied and the electric motor is driven by the wheels instead of the other way around, its internal resistance can function as a brake while generating a current, because the rotors (winding coils) continue rotating around the stator (magnetic core). This process is called induction. Almost all modern cars use this peculiarity of the electric motor to largely dispense with the need for mechanical braking. On the one hand, this increases the range (see regenerative braking) and, on the other, allows you to operate the car with just one foot. It’s only when the car can be brought to a complete halt that you can speak of one-pedal driving.
Phase: The European electricity grid supplies households with three-phase power. In simplified terms, this means you’ve got three cables, each of which provides 230 volts. If you picture a circle, the individual phases L1, L2, and L3 each make up 120°. Electrical consumers can use one or more of these phases simultaneously. Normal household appliances usually only need one phase. Things like a stove, sauna and even a home EV charging station use all three phases. At the usual intensities of 16 or 32 amps, this provides a current of up to 22 kW.
Pre-heating: The charging power a battery can accept depends heavily on the temperature of its cells, among other things. If it’s cold, the car initially charges very slowly and uses part of the charging current to heat up the battery. Once it’s warm, the internal resistance drops, and the battery can charge at a higher current. Modern electric cars have the option of pre-heating the battery. This usually happens automatically when the navigation system schedules a charging stop along your route. Some vehicles also allow manual pre-heating.
Range: Range needs little explanation. The range tells you how far you can drive with a full battery, or with your current state of charge. That’s it. And yet this is one of the most hotly debated topics in the world of electric vehicles. On the one hand, this is due to the range anxiety, which is the still prevailing fear of getting stranded with an empty battery, and, on the other hand, to the manufacturer’s often highly inflated range claims. They’re simply not achievable in everyday life. Some might say that’s not true. Granted, if you turn off the heating and follow a truck closely at 80 km/h, you could achieve the WLTP range ;-).
Regenerative braking: This refers to the act of using the motor to slow the wheels. Using standard disc or drum brakes that rely on mechanical friction only results in kinetic energy being converted into heat that simply dissipates. An electric car, however, can feed the energy back into the battery, regardless of whether it’s a hybrid or an all-electric vehicle. In that case, the electric motor acts like a generator and generates current inductively. With many EVs, the level of regenerative braking can be adjusted in several stages. Others, like Tesla, have removed this option from the menu in favour of a fixed high setting.
SoC: The battery level is often referred to as the state of charge, abbreviated to SoC. The SoC is typically expressed as a percentage and always adds up to 100% when adding it up with the depth of discharge (DoD).
SoH: When evaluating a battery, its state of health, or SoH, is much more important than the SoC. This value describes how much of the battery’s gross capacity can still be used and is also expressed as a percentage. If, for example, a battery has a gross capacity of 70 kWh, but the current SoH is 95%, it only has a usable capacity of 66.5 kWh. As such, the battery has already aged (see degradation). When buying a used EV, you should ideally have the SoH checked in a workshop that specialises in EVs.
SuC: Often confused with SoC, this a common abbreviation for Tesla’s own charging stations called Superchargers.
Supercharger: The Supercharger network owned by Tesla and, until a few months ago, exclusively available to vehicles of the American brand. The Superchargers are now open to all EVs in numerous countries such as Germany, the Netherlands, Belgium, France, Spain and Great Britain. According to Tesla, however, this availability is still in the pilot phase and subject to some limitations. The latest generation Superchargers offer a maximum charging power of 250 kW.
Synchronous motor: In a synchronous motor, the rotor and the stator magnetic field spin synchronously. There are two types of synchronous motors:
- Permanent Magnet Synchronous Motor (PMSM): If performance and efficiency are the top priority, there is no way around the permanent magnet synchronous motor. In this kind of motor, powerful permanent magnets are used to generate the magnetic field in the stator. However, PMSMs drive up production costs significantly. It also requires rare earth elements, which applies to the production of many ebike motors, too, by the way. However, PMSMs are comparatively light, compact and energy efficient.
- Separately excited DC motor: In the case of a separately excited DC motor, an electromagnet generates the required magnetic field by means of a coil through which current flows. On the production side, this is simpler and cheaper than the production of a permanent magnet synchronous motor. This is one reason why separately excited DC motors are often used in smaller and lower-performance vehicles.
Type 1 plug: This plug was specially developed for charging EVs with alternating current and is mainly used in the Americas and Asia. In addition to allowing energy to flow through it, the plug also communicates with the car charger. Since the Americas and Asia only have single-phase power grids, EVs with type 1 plugs can charge at a maximum of around 7.4 kW in Europe, which corresponds to 22 amps at 230 volts. In fact, German households are only allowed to have about 4.6 kW on one phase, otherwise you can have an imbalanced load, resulting in disturbances in the power grid.
Type 2 plug: While America and Asia rely on the type 1 plug, Europeans have the type 2 version, developed by MENNEKES, therefore, also referred to as MENNEKES plug. Like its type 1 counterpart, the type 2 plug also allows for the flow of both energy and data. Thanks to the three-phase technology, the maximum charging power via type 2 is 43 kW, though private households usually can’t get more than 11 kW via a home EV charger. Going higher would require approval from the network operator. At 230 V and 16 amps, a domestic European outlet usually has a maximum output of up to 3.6 kW. However, you should have an electrician check your wiring beforehand and install a socket that can handle a continuous load.
WLTP: The Worldwide Harmonized Light Vehicles Test Procedure is a standardised test cycle used to determine the fuel or power consumption of a vehicle. The results from the WLTP test serve as a basis for many electric car manufacturers when indicating the range of their vehicles. However, these theoretical values are impossible to achieve in reality, especially at low temperatures. Quite the opposite: in winter, the actual range may well be 30 to 50 percent below the manufacturer’s specifications.
Words: Patrick Gruber Photos: diverse
