- Structure These are the components of a wallbox
- Plug types There are different plug types depending on the vehicle and country
- Charging power and charging time What this means for e-car buyers
- Security An overview of important protective functions
- Smart charging As with other devices, smart charging is also possible here
- Additional functions What you need to know about load management, energy meters and more
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.
Typical structure
In most cases, a wall charging station has the following elements:
- Suspension device/ stand
In garages in particular, wall-mounted charging stations are attached directly to the wall in keeping with their name. However, as this is not always possible - for example in some carports - a stand can often be ordered as an accessory. The wallbox can also be mounted on a wooden wall. However, it is advisable to place a fireproof material between the wall and the wallbox. - Cable
The charging stations are usually equipped with one or two charging cables. This distinguishes them from public charging stations, where you usually have to take your own charging cable with you. However, there are also wallboxes that only have sockets. - Holder for cable and/or plug
Many models are equipped with holders for the cable and plug, which not only keep things tidy, but also protect the plug from dust and moisture. Alternatively, they are also available as accessories. - Plug
The plug or socket must always be matched to the electric car. But don't worry: if you change the electric car and thus the plug type, you can remedy the situation with the appropriate adapters. - Housing
The heart of the wallbox is hidden in the housing. There are also weatherproof versions that are suitable for carports, for example.
Plug types
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.
Plug for AC charging
Household plug, Schuko plug
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
Type 1 plug
Especially common in Asia
Maximum charging power: up to 7.4 kW, single-phase
Charging cable: Mode 3
Type 2 plug, Mennekes plug
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
Plug for DC charging
CCS plug, Combo 2
extended type 2 plug; widely used in Europe
Maximum charging capacity: up to 350 kW
CHAdeMO
Japanese standard; mainly used in Asia
Maximum charging power: up to 150 kW
Tesla Supercharger
Very similar to Type 2; only for Tesla vehicles
Maximum charging power: up to 120 kW
Charging power and charging time
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 ÷ 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.
Security
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:
Smart charging
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.
Other additional functions and devices
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.
Load management - optimal charging of several e-cars
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:
- Static load management: The electricity is distributed evenly between the connected electric cars.
- Dynamic load management: The charging power depends on the power currently available and includes other consumers in the household.
Electricity storage - a useful addition to the PV system
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.
Energy management - optimizing power consumption
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!
Electricity meter
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.
Energy meters that comply with measurement and calibration law
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-certified energy meter
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.
Not suitable for billing: Simple energy meters
Simple meters provide an overview of how much electricity has been consumed, but are not intended for billing employers, apartment buildings, etc.
Separate electricity meter
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.
Solutions for duplex garages
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.
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