Teardown - What's in the Tesla Wallbox and how does it work?

At the beginning I would like to briefly clarify the terminology. Especially when it comes to Tesla products, some people seem to get confused:

  • Superchargers, these are Tesla's large fast charging stations with CCS and at least 150 kW
  • Wall Connector, these are the small wall boxes from Tesla with type 2 and 22 kW
  • Universal Mobile Connector (UMC), these are Tesla's mobile charging cables with 7.2 kW to 11 kW for everything from the standard socket to the high-voltage socket

This is about the Tesla Wall Connector, the Wallbox from Tesla. The model shown here is exactly the third generation of this, which is on sale since 2019. Like any other wallbox, it works for all vehicles with type 2. This means that every European car of every brand can be charged with it. In terms of content, all modern wallboxes work very similarly, so this one is a nice example to illustrate the structure of a wallbox.

The same applies for Wall Connectors for the USA with Typ 1 and NACS, the only difference being that those are only equipped with a single phase, not three phase power.

Tesla has also implemented a function that allows you to set the Wall Connector so that it only charges Tesla vehicles. This can be set at any time in the Wall Connector settings. The Wall Connector receives firmware updates of Tesla vehicles when are charged to it. Tesla vehicles can also access any error codes and display them on the display in the car. Directly with the explanation of what the error code means and what you can do about it.

The built-in Type 2 cable also has an integrated button with which the Tesla's charging flap can be opened.

Tesla Wallconnector gen2 & gen3

I personally have several Tesla Wall Connectors because they can also be set up with a static load management. More about it here:

My own public charging station, in addition to 5 private charging points

Teardown of the Tesla Wall Connector

For this article, I have already unscrewed the Wall Connector from the wall and placed it on my desk. The first step is to remove it from its wall plate.

Step 1 – Disconnect the actual Wall Connector from its wall plate

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The Wall Connectorhas two screws at the top and bottom. These must be removed so that the Wall Connector with the type 2 cable and everything can be removed from the wall. This structure allows it to be replaced very quickly if, for example, it is defective.

Step 2 – The Wall Connector and the wall plate

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

At the bottom we see the wall plate, above the actual wall box. After the screws have been loosened, you can easily remove them from the wall plate. The wall plate itself has an input at the top and bottom to supply power to the wallbox. It is preferable to connect it from below so that water cannot run into the wallbox through the supply line.

In the wallbox you then have the connection terminals for grounding, the neutral conductor, 1st line conductor (L1), 2nd line conductor (L2) and 3rd line conductor (L3). These come into contact with the actual wall box via the box's contact blades in the sliding contacts on the wall plate. The wallbox itself has an unused RS-485 port and a temperature sensor. This keeps an eye on the temperature of the wall plate and can detect if there is overheating at the transfer points.

Step 3 – Remove the glass plate from the front

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The glass plate on the front of the Wall Connector is held down by two screws. After these have been loosened, the plate can be hung out at the top. This has the advantage that it can be replaced in the event of damage. In addition, Tesla offers these glass panels individually in different colors, so that you can customize the Wall Connector quite easily.

What is also difficult to see here is the rubber seal in the housing against the wall plate.

Step 4 – Remove the waterproof and clear front panel

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

To get to the inner workings of the Wall Connector, you have to loosen eight screws. The front panel can then be removed.

Step 5 – LED strips and RFID reader

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

Now we see a dedicated circuit board at the top. This is plugged into a connector on the main board of the Wall Connector with a flexible cable. On the dedicated circuit board we find the LEDs for status display during charging and an unused RFID coil. The latter could be put into operation with future updates and an activation of the Wall Connector could be implemented.

The dedicated circuit board itself is mounted on three plastic feet and jammed between them and the front panel.

Step 6 - WiFi antenna

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

A flexible cable runs from the main circuit board of the Wall Connector to a flexible WLAN antenna, which is glued to the upper inner wall of the housing. This connects the Wall Connector to the home WLAN and other Wall Connectors for static load management.

Step 7 - Removing Type 2 Cable

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The type 2 cable is clamped into the housing via a strain relief, which itself is secured in the housing with two screws. This means that any tension on the cable is diverted via the housing and does not put any strain on the connections on the circuit board.

The Type 2 cable itself comes with neutral, 3rd line conductor (L3), 1st line conductor (L1) and 2nd line conductor (L2) screwed directly onto the motherboard. The grounding is routed from the wall plate as directly as possible to the Type 2 cable and the motherboard using its own screw. We'll see it a little better later.

Type 2 cables come with four colored cables for communication:

  • Purple is for the CP signal
  • Orange is for PP coding
  • White is earth again
  • Cyan is the temperature sensor

These are more signals than required by the Type 2 standard. Which opens up additional opportunities for Tesla. I explain how the Type 2 signal works in detail in this article: Type 2 in detail - How does it actually work?

Step 8 - Removing the motherboard from case

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The motherboard is secured in the case with five screws and another screw ensures that the board is grounded. You can also see the transparent front panel with its black sealing strip.

Step 9 - Motherboard and its connectors on the back

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

Here we can see again the wonderful grounding of the motherboard and Type 2 cable. As indicated, the pin that creates the connection to the wall plate. The whole thing is made from a single curved laser part.

We also see the RS-485 port again and the pins for the phases and the neutral conductor. In addition, the temperature sensor.

Step 10 - The Top of the Motherboard

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The largest components here are the two HV contactors. These are what you hear with a *clack* shortly before the charging process starts. Below we have three coils, one for each phase. These measure the actual charging current. They would stop the charging process immediately if more current was drawn than allowed. In addition, it allows the static load management to work more precisely.

At the top we also have the power supply for supplying all processors and the like on the motherboard with low voltage.

Step 11 - The installed residual current meter

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

The plastic cover has been removed and you can see the power-conducting bent rails that lead the power from the wall plate through this round box to the HV contactors.

The round box itself has several coils integrated and each one wraps around one of the bent rails. These are the coils that measure the currents very precisely and compare them with the current on the neutral conductor. Together this results in the sensor for residual current measurement. If this detects an error, the HV contactors open immediately and thus stop the charging process.

Thanks to this solution, you don't have to install an expensive Residential Current Detection (RCD, Typ A + DC 6 mA) in the distribution box in addition to the wall box.

Step 12 - The Back of the Motherboard

Teardown - Was ist in der Tesla Wallbox drin und wie funktioniert sie?

Last but not least, let's take a closer look at the back of the motherboard. What is particularly noticeable are the areas where the power-carrying bent parts go onto the main board and into the HV contactors, only to come out again shortly below and go onto new bent rails. All of this is available here again for 2nd line conductor (L2), 1st line conductor (L1), 3rd line conductor (L3) and neutral. All of these power-carrying parts are routed thickly through the entire board and only have very short paths on the board itself.

The shiny coating on the entire board is also nice to see here. It's on both sides. The purpose of this is to protect the circuit board and the small components on it from low levels of moisture and to make the Wall Connector more durable overall.

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