The most important terms regarding electric cars

Glossary electric mobility: All definitions to look up

PSM, CCS, and BEV? Even people who know a lot about conventional vehicles sometimes come up against their limits when confronted with the new terms used in association with e-mobility. However, in order to be able to talk about such systems and the vehicles they are used in, we’ve therefore put together a glossary to help you along here.

A to D

AC (alternating current)

AC (alternating current) is the normal current that comes out of a socket in your home. The reason why it’s called alternating current has to do with the fact that unlike direct current (DC), alternating current periodically changes the direction it flows in. Electric vehicles can “fill up” on alternating current, but the batteries they run on operate with direct current. This means that alternating current has to be converted into direct current before it can be used by the vehicle. This is either done at the charging station itself (DC charging station) or in the vehicle (e.g. when a socket at home is used). Conversion in the vehicle is limited, however, so AC charging generally takes longer than DC charging.


The ampere (A) is a physical unit that denotes the strength of an electric current. The amperage is the amount of electric current that flows through a power cord or line. Electrical devices are always designed for use with a certain current that should not be exceeded. Current, along with voltage (see VOLT), plays an important role in electric mobility (e.g. with regard to the charging process). By way of comparison, An iPhone needs less than two amperes of current, while an electric vehicle needs as much as 500 amperes.


See Lithium-ion battery.

Battery balancing

Battery balancing maintains all the cells of a battery at the same voltage level. This is the basis for efficient battery operation and a long service life.

Battery cells

Lithium-ion battery cells can have different shapes — there are cylindrical cells, pouch cells, and prismatic cells. Mercedes-Benz has opted to use batteries with prismatic cells. These are of the approximate shape and size of a paperback book, each in its own housing, and are sturdy and easy to work with.¹


BEV stands for battery electric vehicle. This term is used for vehicles that are completely powered by batteries. By contrast, plug-in hybrid electric vehicles are known as PHEVs.

Bidirectional charging

Electric vehicles are true all-rounders. For example, they can not only be charged with electricity but also theoretically store surplus electricity and then feed it back into the grid. This is known as bidirectional charging. Electric vehicles could in future be used to temporarily store surplus electricity in this way, feeding it back into the grid when required. One way surplus electricity is created is when wind and solar power facilities produce more electricity than is actually consumed at a given time. People who own electric vehicles could actually benefit financially in the future by storing such surplus electricity — e.g. in a smart grid system, an electric vehicle parked in a garage could make money for its owner while it’s not being used. Not all vehicles and charging stations support bidirectional charging yet, however, and the power grid still needs to be modernized somewhat before we’ll be able to earn extra money in our sleep with an electric vehicle. Still, it’s an exciting prospect to think about.


CCS is an international charging standard for electric vehicles. The CCS Combo 2 fast-charging connector is now the standard for the European market, while the somewhat differently shaped CCS Combo 1 connector is used in North America. The German Charging Station Ordinance now mandates the use of CCS Combo 2 connectors at all new DC fast-charging stations in Germany. The standardized connector system enables both DC and AC charging. There are also other fast-charging standards beside CCS. Examples include Japan’s CHAdeMO system, GB/T technology in China, and the Supercharger system from Tesla.

CCS charging with an output of more than 150kW is referred to as HPC (high-power charging).

CHAdeMO (Charge de Move)

This is a Japanese rival to the CCS standard. The connectors used with the two standards are not compatible.


This is a charging standard that is being jointly developed by Chinese and Japanese companies. The goal is to achieve a charging power of up to 900 kilowatts — but this is still a long way off.

Charging power

If you want to figure out how long it will take to fully charge an electric vehicle, you need to know something about charging power, which is measured in kilowatts. A normal household socket has an output (charging power) of around 2.5 kW. This is a lot less than the power of an AC charging station (approx. 10–20 kW), which in turn has a charging power lower than the current maximum of 400 kW for a DC charging station (like those operated by Ionity). In order to calculate the charging time, you also need to know the capacity of the vehicle’s battery. More specifically, charging time equals battery capacity divided by charging power. If, for example, a vehicle battery has a capacity of 40 kWh, it will take around two hours to fully charge it at a station with a charging power of 20 kW.

Charging stations and connectors

There are basically two different types of charging stations: AC stations and DC stations. It’s easier to install an AC charging station at home. This option is also recommended, given the fact that one’s vehicle is usually parked at home longer than anywhere else (e.g. at night), and this allows sufficient time for charging. DC charging stations [LINK DC] are better suited for charging while traveling (e.g. on highways). They charge the vehicle using direct current. Direct-current charging stations cost more and need to have a high current rating than is usually available in a private household. Fast-charging stations with more than 100 kW capacity are now commonly referred to as ultra-fast charging stations, while a home charging station is often called a wallbox.

There are also different types of connectors and cables for battery charging. A Mode 2 charging cable enables emergency charging of an electric vehicle using a normal household socket. Mode 3 charging cables are used to connect a vehicle to a charging station.

The connectors used with the cables differ, however: Type 1 connectors are utilized mostly in North America and Asia, while Type 2 connectors are common in Europe. Other types of connectors are the CCS Combo connector, which also enables fast charging, the CHAdeMO connector from Japan, and the Tesla Supercharger connector.

References to Mennekes connectors are quite common. Mennekes is the name of the manufacturer, and usually refers to a type 2 connector when used in this way.

DC (Direct current)

This is the counterpart of alternating current (AC). Electric vehicles can only store direct current, which means alternating current must first be converted to direct current using a voltage converter. This can be done either in the vehicle (home charging) or at a charging station.

DoD (Depth of discharge)

DoD refers to the extent to which a battery is emptied relative to its total capacity. A very deep discharge will increase vehicle range, but it will also have a negative impact on battery service life.

E to L

Electric motor

An electric motor converts electrical energy into mechanical energy. Here, current-carrying coils generate magnetic fields with mutual attractive and repulsive forces that create rotational movement, which in turn powers the vehicle. A conventional combustion engine uses a process of combustion to convert fuel into mechanical energy.

Emission-free driving

All-electric vehicles are locally emission-free, which is to say they emit no exhaust gases (e.g. CO2) while in use. However, depending upon how the electricity they use is generated, emissions may still be produced — for example in coal or gas-fired power plants. If the electricity used to power the vehicle is obtained from renewable energy sources, the carbon footprint will be even better. If other emissions besides CO2 are taken into consideration (e.g. particulate emissions), then other factors come into play. That’s because particulate emissions are not only caused by exhaust gases but also by wear on road surfaces and tires.

Energy density

The energy density is the amount of energy that can be stored per unit mass or volume of a battery. It therefore has a major influence on battery weight. Energy density is expressed in kilojoules (kJ) or kilowatt hours (kWh) per kilogram. If an electric vehicle battery has an energy density of 140 Wh/kg and requires 20 kWh to travel 100 kilometers, its weight for each 100 km of range would have to be 150 kg in order to enable it store the required amount of electricity.

High-voltage technology

High voltage refers to a DC voltage of more than 60 volts. High-voltage components are specifically labeled as such, while high-voltage lines are recognizable by their orange sheathing. All-electric commercial vehicles generally operate on 600 volts or more. Service technicians therefore need to be instructed and trained in how to handle high-voltage components. The format and complexity of this training will vary depending on the actual tasks the technicians need to perform.¹

HPC (High Power Charging)

HPC is the official designation for any CCS charging procedure that involves a charging power of more than 150 kW.

ISO 15118 charging standard

This standard ensures communication between the charging station and the onboard charge control device. It therefore forms the basis for an active and intelligent charge control system (which is important for vehicle fleet operators in particular) and the establishment of smart invoicing systems.

The ISO 15118 charging standard enables Plug&Charge, a procedure in which communication via the charging connector makes it possible for the charging station to identify the vehicle and then automatically invoice the charging process.


A kilowatt-hour (kWh) is a unit of energy. It designates the amount of energy equal to one kilowatt of power being consumed for one hour. The capacity of the batteries used in electric vehicles is usually given in kilowatt-hours.

Lithium-ion battery

A lithium-ion battery is a rechargeable energy storage unit that converts electrical energy into chemical energy, which it then stores in order to release it once again in the form of electrical energy when needed. When the battery is charged, lithium ions move from the cathode to the anode; during discharge, they move from the anode to the cathode. Lithium-ion batteries stand out through their high energy density and are therefore considered state-of-the art technology for all-electric vehicles.

Well insured: Many customers who are thinking about switching over to an electric vehicle want to know how long their battery will last. After all, no one wants to be left with a relatively new vehicle whose battery has failed after three years. There’s no reason to worry, however, since most batteries last a very long time, as is demonstrated by the special warranties that battery manufacturers offer. Under such warranties, the manufacturer will replace the battery if anything should go wrong with it. The batteries used in Mercedes-Benz vehicles come with a battery certificate as a standard service. This certificate guarantees optimal battery performance for eight years or 160,000 kilometers for BEVs (100% battery electric vehicles). The battery certificate for PHEVs (plug-in hybrid electric vehicles) guarantees battery performance of at least 70%. This certificate is valid for six years or 100,000 kilometers. Mercedes-Benz Cars After Sales and Mercedes-Benz Mobility also offer an appropriate extended warranty for the battery certificate, as well as an extended vehicle warranty that expands the standard Mercedes-Benz new vehicle warranty to cover battery failure or unexpected battery repair costs for a maximum of 10/12 years of vehicle ownership or 200,000 kilometers.

Mercedes-Benz Mobility offers a matching warranty extension, which covers all other high-voltage components. This enables Mercedes-Benz Mobility customers to extend the manufacturer's warranty up to ten years or 200,000 kilometers.

In addition, Mercedes-Benz Bank and its insurance partner, HDI, are now offering a new electric protection component that provides extensive insurance coverage for hybrid and electric vehicles. The component is automatically added to comprehensive insurance policies for electric and hybrid vehicles, entails no additional cost for the customer, and basically offers all risks coverage for the battery.

P to W

Power electronics

The power electronics are made up of several components contained within a single housing. The DC/AC converter, also known as an inverter, converts direct current into alternating current. The DC/DC converter or voltage converter, also known as a DC voltage transformer, converts incoming DC voltage into higher or lower DC voltage.

Peak output

The peak output of an electric motor is comparable with the figure given for the rated output of a combustion engine and corresponds to the maximum possible output that is temporarily achievable. Another figure used is that for continuous output, which represents the maximum output that can be called upon for an extended period.

Permanent magnet synchronous machine (PMSM)

In the case of internal combustion engines, we distinguish between diesel and gasoline engines — but did you know there are also different kinds of electric motors? Here, a distinction is made between a PMSM (permanent magnet synchronous machine) and an ESM (electrically excited synchronous machine), whereby the latter is currently rarely used in electric vehicles. PMSMs are more common here. The difference between PMSMs and ESMs involves the magnets used — i.e. PMSMs use permanent magnets and ESMs use electromagnets.


PHEV stands for plug-in hybrid electric vehicle. Unlike vehicles that run completely on batteries (BEVs), the batteries of PHEVs can be recharged via either the power grid or a combustion engine in the vehicle itself.


In a Plug&Charge system, the charging connector enables the charging station to identify the vehicle being charged, which in turn makes it possible to automatically invoice the charging process, for example. This aspect is particularly interesting for operators of vehicle fleets. See ISO 15118 charging standard.

Power availability display

This is a display in the instrument panel that replaces the tachometer found in vehicles with a combustion engine. The power availability display shows the level of power being drawn by the drive systems at any given moment. It also shows the power being recovered during braking and overrun mode (coasting).

Recharging battery

As its name suggests, a rechargeable battery is an energy source that can be recharged. Rechargeable batteries that are used to power an electric vehicle are generally referred to as high-voltage batteries or drive batteries. Such batteries need a power connection to be recharged, and most electric-vehicles currently use lithium-ion batteries.

Well insured: Mercedes-Benz Bank and its insurance partner, HDI, are now offering a new electric protection component that provides extensive insurance coverage for hybrid and electric vehicles. The component is automatically added to comprehensive insurance policies for electric and hybrid vehicles, entails no additional cost for the customer, and basically offers all risks coverage for the battery.


Recuperation is also known as braking energy recovery or recuperative braking. It is a process in which kinetic energy is converted into electrical energy. Basically, this means that part of the energy recovered during the braking process is used to charge the battery.

SoC (State of Charge)

The SoC is shown on a display in an electric vehicle that corresponds to the fuel display in a vehicle with a combustion engine. The display shows the amount of energy currently available as a percentage of the battery’s maximum storage capacity. Just about everyone is familiar with the battery charge indicator in a smartphone, which is usually located in the upper corner of the display. This is also an SoC display.

TCO (Total Cost of Ownership)

The high purchase price of electric vehicles is frequently used as an argument against them. However, other factors also need to be considered when determining whether an electric vehicle or a vehicle with combustion engine is the better choice financially. These factors relate to maintenance and upkeep — i.e. the cost of fuel/electricity, maintenance, servicing, and residual value etc. While electric vehicles are usually more expensive than vehicles with combustion engines, the situation is often different when you consider their entire useful life. Total cost of ownership refers to all costs incurred throughout the entire life cycle of a vehicle.

Athlon and Daimler Mobility have developed a TCO simulator for fleet managers that helps customers decide whether an electric vehicle makes sense for them The simple comparisons enabled by the simulator will make it easier for our customers to switch to electric vehicles.

Ultra-fast charging

Some people are still skeptical when they think about taking a long trip with an electric vehicle — and the fact is that certain conditions do need to be met in this regard. One of these involves the existence of an extensive network of ultra-fast charging stations, which are often also referred to as HPC (high-power charging) stations. These stations can have an output of as much as 400 kilowatts, which means they can charge vehicles more rapidly than a normal fast-charging station. Through its participation in the Ionity joint venture, Daimler is also helping to build such an ultra-fast charging network.


The volt (V) is the unit of difference in electric potential. Both voltage and amperage (A) influence the output of an electric motor, as well as charging power and charging time.


A home charging station is often referred to as a wallbox because it is mounted on a wall — i.e. it is not a free-standing unit. Wallboxes generally use alternating current to charge a vehicle, which then converts the AC into direct current. While DC wallboxes do now exist, they are mainly used in connection with bidirectional charging. Normal household sockets are generally not suitable for the constant charging of electric vehicles because they are not designed to handle this type of electric load. Wallboxes offer the appropriate interface for this use.

Customers who buy a Mercedes plug-in hybrid or electric vehicle can also purchase a wallbox directly (installation included) from The Mobility House, which is a Mercedes-Benz partner. In selected markets, Mercedes-Benz Mobility offers vehicle-financing packages that include a wallbox, and the company is now considering the inclusion of wallboxes in leasing agreements in various markets as well.

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