General information about my public charging station
The charging station itself was left over from Sm!ght, an EnBW subsidiary and is an in-house development. My charging station is an "EnBW LS 3.0" with the 3.2 doors that comply with the German "Eichrecht", which is a very complicated calibration law. Mine in particular was a remainder which I bought. You can find out how I installed this charging station in my garden and now operate it in this article: My public 22 kW charging station
Heidelberger now sells the heritage of the Sm!ght stations and develops them further with its subsidiary Amperfied GmbH.
In another article I'm also going into more detail on how to operate a charging station on the same private grid connection with five other wallboxes for electric cars without blowing breaker: My own public charging station, in addition to 5 private charging points
The charging station from outside
Everyone already knows the display from the front and the RFID readers and some might already have noticed also a barely visible brightness sensor above the display. There is also a plastic cap on the charging station, underneath which is the LTE/WLAN antenna for internet access. If the charging station is not connected via Ethernet, like mine is, the charging station accesses the Internet and its backend with the antenna there.
What's a backend and how does the money from the costumer finds it's way over the charging card provider to the charging station owner is explained in great detail here: How does the money actually get from me to the charging station operator? (feat. smart charge@street)
The charging station also has two doors, one on the right and one on the left. I'll explain what exactly is behind the doors further down below. What's interesting about the doors is that each side has two locks. However, this is not because two people have to be on site to open the doors, but on the contrary: Both the charging station operator has the key to one of the locks and the power grid operator has the key to the other lock. This means everyone can open the charging station independently of each other and access their parts.
Since my charging station does not run on its own separate grid connection, there are no locks installed for the network operator.
There is also an viewing window in the left door, through which you can view the electricity meter readings of the two charging points at any time. In more modern charging station this is solved digitally, in this charging station from 2017 this is still analoge like this. Since today's German calibration law had not yet been invented back then, I had to retrofit the electricity meters and the viewing window that complied with calibration law.
In this case, it is easier to comply this way to the rules, than by digitally integrating the electricity meter into the display.
The electricity meter are also beein read out digitally for the billing process. But in addition to that the customer in Germany also needs to be able to check the overall power which was transfered over them. So he can compare that to before he started charging and after he's done.
The most important thing is of course the connections for electric cars on the right and left. Both sides have a Type 2 socket with 22 kW and a Schuko socket with 2.3 kW. The latter is outdated these days and is practically no longer used on my charging station. But since I'm curious to see who uses it, I still have it in use.
The charging station from the inside
If you now open the doors of the charging station, you practically have two areas: On the right is everything that concerns the charging station's grid connection. So the armored fuses, space for an electricity meter, the main fuses of the charging points. On the left is everything the charging station itself needs. From the control electronics, breakers, contactors to the communication and linking together of all necessary components.
At the top, on the right and left, are the connections through which cars can be connected for charging.
The right side - Everything the power network operator needs
For a first overview, a picture of the entire right side. It starts at the bottom with the grid connection box and above that is the electricity meter space and the main fuses of the charging station.
In newer generations of this charging station, everything is structured in such a way that this is visually in the same place, but from a technical point of view it is no longer screwed into the charging station. Instead, the grid connection box and electricity meter are screwed onto the base plate of the foundation. The charging station operator can then pull the charging station upwards without having to touch the grid connection box and electricity meter. This has the advantage that you can replace the charging station without having to contact the network operator, as you no longer have to touch your things.
As already mentioned, it starts at the bottom with the grid connection box. In my case. There are no armored fuses, just bridges that pass the electricity on to the rest of the station. The reason for this is that I operate the charging station via the grid connection of our house.
Charging station that are operated free-standing and do not belong to any house have 80 A fuses installed here.
The electricity meter position then comes above the grid connection box. If the charging station were connected directly to the grid connection box via its own power connection, it would of course also need an electricity meter. This is practically the same as what you have at home in your apartment. In my case the electricity meter space is empty.
The last component on this page comes above the electricity meter. From left to right we have the main breaker of the charging station with 63 A and then another 40 A circuit breaker for each charging point.
The left side - Everything the car and the charging station needs for it
On the left side it goes from bottom to top again. It starts at the bottom with the breakers for the charging points, like the contactors. Above these are the two residual current switches and lastly in this box are the electricity meters and a breaker for the control electronics of the charging station. Last but not least comes the entire control electronics itself.
So it starts with the 16 A circuit breaker for the Schuko charging socket and next to it is the 32 A breaker for the type 2 socket itself. Here and in the other three following pictures you also notice that the right and left sides in the photos operate the right and left charging points of the charging station. The structure is practically symmetrical and the same for both sides.
Next, above the breaker for the charging points, is the residual current switch. This is responsible for tripping when an electric car has a fault current of over 0.03 A, which would indicate a defective car charger. Renault Zoe drivers in particular know this switch all too well.
To the right of the residual current switch is the so-called motor drive. This is practically a servo that can automatically reiset the residual current switch. Precisely because this often triggers incorrectly from a Zoe and generally only because of a car, the charging station has an automation in the background that activates it again up to 3 times. In addition, it can be reset remotely by a technician, so you don't have to send someone to the charging station in the field at great expense.
Finally, at the top there are the two electricity meters of the charging station, which count the consumption of the electric car and communicate their values to the backend for billing. In order to comply with all German regulations, these are at the top and as close as possible to the charging points so that the distances are as short as possible.
On the far left there is also a 16 A circuit breaker for the internal control electronics of the charging station.
So far we have mainly seen the path of the charging current, hence large circuit breaker for large currents. But ultimately the most complex thing is not to bring the electricity to the car, but rather to manage the billing, load management and the display with its RFID readers. All the control electronics are there for this purpose.
This is where not only most of the charging station's know-how is located, but also the most complex components.
On the far right we have a Raspberry Pi, which is responsible for controlling the display, part of my administration interface and parts of internal communication. It is also the so-called sensor controller for functions that are historically supported but are not used anymore.
Next to it we have the two yellow Bender controllers. These bear the name of their company and are primarily responsible for communication between the charging station and the car. They also manage the internal load management and for this purpose also have a current clamp, which is not visible here. This is commonly referred to as a Bender ring. Its purpose is that the charging station keeps an eye on how much current each car car is actually drawing and whether it has finished charging.
The Bender controllers also provide calibration law-compliant communication between the charging station and the backend.
There is also a classic 12 V power supply between the Bender controllers. This is nothing more than a standard 12 V power supply for a laptop or the like, but in a form factor so that it can be operated in such an installation. It is powered with AC 230 V via the 16 A circuit breaker shown in the photo above and supplies all the electronics here with DC 12 V and up to 55 W.
Next comes a small distribution unit through which the 12 V is distributed to all components. Followed by the silver box, this is the internal router through which the charging station communicates with the internet and everything is connected internally via Ethernet.
Lastly comes the so-called SensorcoltrollerExpention. This is an extension of the Raspberry Pi and is unnecessary for the charging station service. It is part of the unused functionality of the charging station. Other expansion stages of this charging station can also measure environmental values such as air quality and this is then done via this controller.
Because the question came up and I would like to address:
Type 2 charging stations usually do not have any heating or cooling installed, so neither does mine. With type 2 charging stations and AC charging processes in general, the charger is located in the vehicle and the waste heat from the charging process is generated there by the power electronics. Nothing in the charging station itself gets noticeably warm. Even while charging 22 kW, everything gets lukewarm at most.
Only during CCS charging does the power electronics, which produce waste heat, move into the charging station. From 100 kW onwards, the output is also high enough that cooling the charging cable starts to make sense.
Final conclusion and information about the charging station
My charging station is technically still in 2017. Nowadays you no longer have everything as detailed and beautiful as DIN rail components with a dedicated Raspberry Pi, router, switch and so on. In order to save costs, more and more charging stations are now relying on dedicated circuit boards. Which are easier to scale. However, due to your own grid connection and the complex technology for public charging stations, they can never be as compact and small as a wallbox. Even if you use a dedicated electricity meter connection post for all the grind connection and electricity metering things.
Even though public charging station have no difference from a private wallbox from the car's perspective, there is still more going on in the public charging stations. Even without the German calibration law-compliant billing, they have to process data and everything else expected from public charging stations.
For me personally, the layout of this charging station has the great advantage that everything is made from very simple standard components. This makes its maintenance and operation easier for me. Because I am not dependent on the manufacturer of the charging station. Nevertheless, this flexibility was also costly, which made the charging station increasingly uneconomical for large operators.
Amperfied GmbH is now selling the legacy of these charging station and has revised the entire interior accordingly. From a technical point of view, all modern Type 2 charging stations still work on practically the same principle as my public charging station.
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