CHARGING BASICS 101: How to charge an Electric Vehicle: Plug-in, Battery Swap & Wireless charging

There are three basic ways to charge an electric vehicle: plug-in charging, battery swapping or wireless charging. This article may give an overview about all these three ways of charging electric vehicles.

1. Plug-in EV charging

Plug-in charging is used by the vast majority of current BEVs and PHEVs in Europe. Vehicles are physically connected to a charging point using a cable and a plug. Plug-in charging can occur wherever charging stations are located: at homes, in public streets or on commercial or private premises.

Electric vehicles can, in general, be charged using normal household sockets, but this is slow because normal domestic sockets provide only a low amount of electric current. It can therefore take approximately eight hours for a typical charge (for a medium sized battery). This can be quite suitable for overnight charging, however. Faster plug-in charging requires specialized infrastructure. To date, most public plug-in stations established at a city, regional or national level offer only normal‑speed charging.

The different types of Electric Vehicle plug-in Charging

There are different ways in which battery electric vehicles or PHEVs can be charged via plug-in charging. Four 'modes' of charging technology are commonly available. Each of them can involve different combinations of power level supplied by the charging station (expressed in kW), types of electric current used (alternating (AC) or direct (DC) current), and plug types.

As electrical power grids provide AC current, and batteries can store only DC current, the electricity provided by the grid to the electric vehicle first needs to be converted. The conversion can be done either by an on-board AC/DC converter inside the electric vehicle or by a converter integrated into the charging point itself. Hence, AC charging is sometimes referred to as 'on‑board charging'. DC fast-charging stations have integrated converters, so the charging station itself converts AC electricity from the grid into DC electricity for the electric vehicle.

The power level of the charging source depends on both the voltage and the maximum current of the power supply. This determines how quickly a battery can be charged. The power level of charging points ranges widely, from 3.3 kW to >350 kW. Lower power levels are typical of residential charging points.

Mode 1 (slow charging): allows vehicle charging using common household sockets and cables. It is commonly found in domestic or office buildings. The typical charging power level is 2.3 kW. Household sockets provide AC current.

Mode 2 (slow or semi-fast charging): also uses a non-dedicated socket, but with a special charging cable provided by the car manufacturer. A protection device that is built into the cable offers protection to the electrical installations. It provides AC current.

Mode 3 (slow, semi-fast or fast charging): uses a special plug socket and a dedicated circuit to allow charging at higher power levels. The charging can be either via a box fitted to the wall (wall box), commonly used at residential locations, or at a stand-alone pole, often seen in public locations. It uses dedicated charging equipment to ensure safe operation, and provides AC current.

Mode 4 (fast charging): also sometimes referred to 'off-board charging', delivers DC current to the vehicle. An AC/DC converter is located in the charging equipment, instead of inside the vehicle as for the other levels.

2. Battery swapping for electric vehicles

Battery swapping involves replacing a used battery with a fully charged one at a special swapping station. This offers a rapid way of quickly 'recharging' a vehicle. At present, no major providers in Europe offer battery swapping.

A number of barriers have prevented battery-swapping technology from becoming widespread, including the lack of electric vehicle models that support battery swapping, no standard type or size of battery, and the high cost of developing the associated charging and swapping infrastructure.

3. Wireless Charging for electric vehicles

Wireless charging, also known as induction charging, does not require a fixed physical connection between the charging facility and the vehicle. Instead, the system creates a localized electromagnetic field around a charging pad, which is activated when an electric vehicle with a corresponding pad is positioned above it.

The wireless method currently operates at only a selected few pilot locations and is yet to be used commercially. Examples of inductive charging pilot projects include wireless charging for buses at bus stations in Belgium, Germany, the Netherlands and the United Kingdom, as well as some pilot testing for users of electric cars in Sweden.

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