Charging Electric Cars on the Road

Essentially, there are two ways to charge an electric car: with alternating current (AC) and with direct current (DC). The charge speed depends on the charging station and on the car.

The power of charging stations, with which they can charge, is indicated in kilowatts (kW). Electric cars have a power with which they can be charged. The lower of both values is the practically relevant one. This is a theoretic maximum value, which up to a battery charging level of about 80% is almost realized. At higher levels, the charging speed becomes notably slower.
One example: a fast charging station can charge with 100 kW, but the car can only be charged with 60 kW. It has a battery with 50 kilowatt-hours (kWh) of energy and is filled to 20%. To fill it up to 80%, which means to charge 60%, 50 kWh * 60% = 30 kWh have to be charged. It is charged with 60 kW, so ideally it takes 30 kWh / 60 kW = 0.5 h, half an hour. Practically it will take a bit longer.

Alternating current (AC) is provided by the plug socket at home and is used by normal charging station. Those usually have a lower power. In Europe, most of them can charge on three phases, but some electric cars can only be charged with one phase, which then takes more time. Keep that in mind when you plan to purchase a car and have to charge often on AC stations. Plug type 1 is used in America, type 2 in Europe.

Type 2 socket
Type 2 socket without CCS at a charging station.

Direkt current (DC) is used by fast charging stations and allows for higher powers and so for shorter charging times. The most common, not compatible systems for fast charging stations are CCS and CHAdeMO, an electric car supports either the one or the other. CCS seems to become the standard in western countries. The plugs are an extension of type 1 or 2.

Renault Zoe charging
A Renault Zoe at a type 2 normal charging station, charging with 22 kW, February 2019.

CHAdeMO socket
CHAdeMO socket at a Nissan Leaf.

Charging at Home - Wall Box

Electric cars can be charged at a plug socket. This takes some time, dependant on the battery size and charging level, many hours up to days. Plug sockets are not made for such a load and so, especially older installations, can have security issues here. So the acquisition of a fixed or mobile wall box is recommended for owners of electric cars.

Wall boxes are, if possible, attached to the strongest electric circuit available, this can e.g. be the circuit for the electric stove. They have a higher power and therefore a faster charge speed. The charging is monitored and safe. The fixed wall box stays in its place. A mobile wall box can be connected to existing electric circuits, whereas an adapter can be needed.

There are many different wall boxes, before the purchase an expert advise is recommended.

Experience Report

During the year 2019 or early 2020, a wall box will be installed into our existing garage. The garage, which was build in 1974 and is 2 meters away from the house, has to be connected to an electric circuit before. A first estimation in February 2019 for the cost of the garage electrification with 16 amperes is about 2000 €. Later, the price for the wall box will add to this.

This garage will first get electricity, then a wall box.


Last change May 28. 2019

No responsibility is taken for the correctness of this information. The articles on this site about electromobility and different electric car models are based on personal experience and on current news. They are not sponsored or supported by the car manufacturers.

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