From the plug to the additional functions - not every wall charging station is the same. We explain the most important differences.
Inseparably linked to the purchase of an electric car is the question of how it should actually be charged in everyday life. The simplest solution is often to use a wall charging station in your own garage. This is because the car is usually parked there for several hours a day (or night), during which it can be conveniently charged. However, the wall charging stations or "wall boxes" on the market differ considerably from one another, so you should always consider which technical design and additional functions you really need before making a purchase. In this article, we provide you with important basic knowledge to help you with your considerations.
In most cases, a wall charging station has the following elements:
Many different plug types were established in Europe before the EU made type 2 the standard. However, the type of plug you need is usually determined by the vehicle.
One of the most important criteria for plugs is whether you are charging with alternating current (AC, single-phase, two-phase or three-phase) or direct current (DC). This is because while only alternating current comes from the mains, the electric car needs direct current. This necessary conversion from alternating current to direct current can be carried out either by the charging station (with a plug for so-called DC charging) or by the electric car (with a plug for so-called AC charging) in the built-in charger (on-board charger).
There are further differences in the cable types that can be combined with the plugs and the maximum charging power. For example, while a type 2 plug enables fast charging, this does not work with a type 1 plug. Depending on the wallbox, there is a difference as to whether a charging cable is already integrated or not. The type of cable plays a particularly important role when charging on the move.
The plug type commonly used in German households; not designed for continuous use - fire hazard!
Maximum charging power: up to 2.3 kW, single-phase
Charging cable: Mode 2
Especially common in Asia
Maximum charging power: up to 7.4 kW, single-phase
Charging cable: Mode 3
EU standard; new public AC charging points must have this connection
Maximum charging power: up to 43 kW, single-phase and three-phase
Charging cable: Mode 3
extended type 2 plug; widely used in Europe
Maximum charging capacity: up to 350 kW
Japanese standard; mainly used in Asia
Maximum charging power: up to 150 kW
Very similar to Type 2; only for Tesla vehicles
Maximum charging power: up to 120 kW
What does the maximum charging power actually mean? It is largely responsible for how long the electric car needs to be charged, because Battery capacity รท charging power = charging time. This means that the higher the power, the faster the charging process.
An example: An electric car with a battery capacity of 45 kWh charges for around 6 hours at a charging power of 7.4 kW and only around one hour at a charging power of 43 kW. Of course, these are only approximate values, as the power is reduced when the battery is charged to more than 80 percent, for example, or before the battery overheats. In addition, a high charging capacity of the wall charging station is useless if the charger installed in the car is not designed for such high values. The actual possible output is always determined by the weakest link in the chain: Wallbox, cable or electric car.
In the case of private wall charging stations, the power connection also sets limits. Charging capacities of up to 3.7 (single-phase), 11 and 22 kW (three-phase) are common. However, permission must be obtained from the grid operator for more than 12 kW. Incidentally, the ADAC recommends wallboxes with a charging capacity of 11 kW: These do not require a permit from the grid operator and also allow charging at 3.7 as well as 7.4 and 11 kW. They therefore offer the greatest possible flexibility.
Most wall charging stations already have simple protective functions. They reduce the risk of an electric shock or short circuit (line protection). A residual current circuit breaker (RCCB) is also required. A distinction is made here between RCD type A for wall boxes with integrated DC residual current detection and RCD type B for boxes without detection.
This may seem a little complicated at first glance, but don't worry: with a specialist electrical company, you are always on the safe side. The electrician knows which type of switch is required for the wallbox.
Access protection is often also recommended to prevent unauthorized use of the charging station, for example in the case of a free-standing parking space or an underground car park to which other people also have access. Simple key switches, PIN codes or card readers (RFID) are widely used.
To avoid defects, wall-mounted charging stations must also be protected from external influences such as the weather or dust. The IP protection class indicates how resistant a wallbox is. This always consists of two digits (e.g. IP 54), which mean the following:
Like fridges and televisions, wall charging stations are also available in "smart" versions. They can be controlled or networked with other devices via WLAN, LAN, mobile radio or Bluetooth and come with numerous new functions. For example, charging times can be programmed or statistics called up. Some charging stations can also be used to control the charging of solar power from your own photovoltaic system. In everyday life, however, a simple wallbox is usually sufficient - which is also good for your wallet.
Additional functions can help to make everyday life with the electric car easier. More technology is naturally reflected in a higher price and an increased range of functions. We therefore advise you to only choose the additional functions that you really need.
Do you live in an apartment building with several wallboxes or do you need a wallbox with two charging points? Then a load management system is worthwhile. It controls how the electricity is distributed. The advantage of this is that the grid connection does not need to be extended and peak loads are avoided. A distinction is made between:
The most environmentally friendly way to charge is to use electricity from your own photovoltaic system. But of course, green solar power is only available during the day, while the car is usually charged at night. The solution to this is an electricity or home storage system. The solar energy is stored in this and used later when needed. It is important that the storage unit is matched to the wallbox. It may be worth buying both from the same supplier.
If you also have the option of "refueling" your electric car at home during the day, you can use the vehicle as an electricity storage unit. There are special systems for this that charge electricity from the PV system into the car when it is not needed at home. It is therefore smart to keep a close eye on any PV surpluses. This is regulated by an energy management system (EMS). If a charging station has an energy management function, it can be integrated into an energy management system (EMS). The EMS digitally records the charging capacity of the charging station and automatically adjusts it to the load on the energy grid. This is because the more self-generated electricity is used for charging, the lower the external power consumption. This saves money!
In most cases, it is not important to know how much electricity is being drawn from the wallbox - after all, you don't know how much the stove consumes. However, sometimes an electricity meter (also known as an energy meter) can be useful. For example, to bill the electricity required for charging to the nearest kilowatt hour. This is necessary, for example, for a shared charging station in an apartment building or for billing electricity costs to the employer for a company car.
Electricity meters can comply with measurement and calibration law, i.e. they meet the requirements of German measurement and calibration law. This ensures that what is actually billed is what is actually used (in kWh). This may be necessary in various cases, for example in an apartment building, for the employer for electricity billing for company cars or if neighbors and acquaintances also use the wallbox.
MID stands for "Measuring Instruments Directive" and specifies various requirements for certain types of measuring devices. If these requirements are met, no initial calibration is necessary - provided there is a corresponding declaration of conformity. This means that MID-compliant energy meters can often also be used for billing purposes, for example for electricity billing by the employer for a company car.
Simple meters provide an overview of how much electricity has been consumed, but are not intended for billing employers, apartment buildings, etc.
Energy meters are also available independently of a wallbox. This does incur additional costs for purchase and installation. However, the electricity used for charging can be measured separately from domestic consumption, making billing easier. In addition, the wallbox does not have to meet any special requirements.
Space-saving garages are particularly widespread in large cities. However, due to the movable floor panels, conventional wall mounting is rarely possible here. However, there are now specially designed devices that are attached directly to the mobile floors and are connected to the home network via a flexible cable.