Frequently asked questions

(2021-09-12)

Yes, there is a charging rule with which you can configure that charging only takes place when the solar system delivers a certain minimum power. In addition, the cFos Charging Manager can handle solar surplus charging. For this purpose, the cFos Charging Manager can read out generation meters and/or directly access the inverters of the solar system. Many SMA inverters and inverters that support SUNSPEC are supported. We are constantly adding more devices to the list. You can also test yourself whether the Charging Manager already supports your solar installation.

What we do not currently support is the automatic switching on and off of individual phases when the solar power drops below 4200 W. This would require us to be able to switch the phases individually using separate contactors. For this, we would have to be able to switch the phases individually using separate contactors. We are considering providing a retrofit kit or conversion kit for the cFos Power Brain Wallbox. However, this will not be possible before 2022.

Here is a workaround: If you know that the solar system delivers less than 4200 watts, you can switch off one or two fuses (circuit breakers) with which the supply lines to the EVSE are protected (just not the one with which the cFos Power Brain Controller is protected). However, you must not switch individual phases on or off during the charging process!

The cFos Power Brain Controller can charge electric cars 1-, 2- and 3-phase. However, your energy supplier and the VDE stipulate that all phases must be loaded as evenly as possible. Individual phases may differ in power by a maximum of 4.5kW from the others. If you have several cars that do not have 3-phase charging, have your electrician connect the EVSEs so that all phases are rotated compared to other EVSEs (phase rotation). You can then configure the phase rotation in the cFos Charging Manager. The cFos Charging Manager then knows on which phases the power is drawn and can take this into account accordingly.

In standby and with a car plugged in, it consumes less than 1.5W. While a car is being charged, EVSE incl. relay and contactor need approx. 8W.

Of course, you must have the cFos Power Brain Controller supplied with three-phase current by an electrician. In addition, you can log the EVSE into your home network via WLAN or dial into your hotspot and operate it via a web interface. You are then ready to go

We recommend that all cFos Power Brain Controllers be connected to your WLAN. This will allow the Charging Manager to communicate with the "slaves" via your home network. Extra cabling with twisted pair wires is only necessary if you want to connect additional Modbus RTU devices

WLAN is sufficient if your cFos Power Brain Wallbox is within range of your WLAN router or an access point. Then you can reach all devices (e.g. other EVSEs via WLAN or network cabling) that can be addressed via IP in your home network. Only if you want to address additional devices that require cabling via RS 485 do you have to install an additional twisted pair connection (e.g. for the ABB B23 / B24 or Eastron Modbus meters, EVRacing EVSE controller, Tesla Wall Connector Gen. 2). If you want to connect up to 2 S0 meters, you will need a twisted pair cable for each meter.

If you operate a single cFos Power Brain Wallbox, it will charge at 16A (11kW) or 32A (22kW) without further configuration, depending on the model. Unless you want to use additional capabilities, you do not need to configure any Charging Manager options. If you want to operate several cFos Power Brain Wallboxs and/or third-party EVSEs on one connection, you will need to configure the cFos Charging Manager if simultaneous charging on all EVSEs will overbook your house connection power.

You can simply install 2 or more cFos Power Brain Wallboxs. One is then the load manager, i.e. master (the cFos Charging Manager is already integrated in the cFos Power Brain Controller) and the other(s) are "slaves". Then set e.g. 11kW or more as the house connection power and the power is dynamically divided depending on whether 1 or 2 cars are charging. I.e. as long as there are not really several cars charging or they are charging on different phases, the charging car receives the full power.
You can also connect an intermediate meter that measures the power consumption of your house (without EVSEs). This way, you could make the entire house connection power available for charging when it is not currently needed in the house.

Yes, the Tesla Wall Connector Gen 2 has an RS485 two-wire interface with which it can be remotely controlled as a slave.

Note: The newer Tesla Wall Connector Gen 3 cannot be controlled remotely at this time.
Tesla is planning a software update at a later date. However, this is currently not available.

You can connect several Tesla Wall Connectors Gen 2 to a bus via RS485 interface and connect them to the RS485 interface of the cFos Power Brain Controller; then you can set up Tesla EVSEs in the cFos Power Brain Controller under "Load Management". Our integrated Charging Manager can then dynamically distribute the available charging power to all charging stations through load management.
Note: The cFos Power Brain Controller can also evaluate and display the actual charging current used and the total kWh consumed for newer Tesla Wall Connector Gen 2.

In the description of the cFos Charging Manager (integrated in the cFos Power Brain Controller or available as a software solution for Windows and Raspberry Pi), you will find a (constantly expanding) list of currently supported EVSEs. In addition, all EVSEs that have sufficient OCPP 1.6 functionality are supported.

The cFos Power Brain Controller has a web interface that allows you to enable charging and set the maximum charge current. You can access the cFos Power Brain Controller's hotspot from your computer and cell phone using your browser. Alternatively, you can also connect the cFos Power Brain Controller to your home network via WLAN and then access the Web interface from your home network

Yes, you can set the maximum charging power in W in the EVSE settings. Effectively, the maximum charging current is then signalled to the car in approx. 1% steps. So you have full control. If load management is activated, the Charging Manager determines the current to which the EVSE is entitled every few seconds.

Some electric cars are put into a standby mode after some time without charging. Example: the car is connected to the EVSE, but charging is not enabled due to a charging rule. Later, when the charging rule is fulfilled and the car is in standby mode, charging does not start by itself.

In principle, the cFos Power Brain Wallbox can wake up cars from standby mode. We are currently collecting empirical data on this. If you would like to test this function, please contact us!

You can test whether a car is "awake" in standby mode if you first deactivate "Charging" under the menu item "cFos Power Brain Controller Configuration" and deactivate the EVSE, i.e. switch off both switches. Now wait 30 seconds and switch both back on.

Does the car wake up?

Putting the car into standby mode can probably be done by setting the charge current to 0mA and waiting until the car is in standby mode, then setting it back to 16A.
We are very interested in your test results!

An Internet connection is required so that the cFos Power Brain Wallboxes can supply themselves with the time. Once they are logged into your home WLAN, you can access them conveniently via browser. Otherwise, you would always have to log in to the EVSE's respective hotspot to use the Web interface

An Internet connection is required for the software updates that we regularly offer for download.

The Web interface of cFos Power Brain Controller is written in HTML and Javascript. Additionally, we use Bootstrap. The display should work well on both desktop screens and cell phones. A reasonably modern web browser is required

The cFos Power Brain Wallbox is supplied with an S0 meter. In addition, there are inexpensive intermediate meters up to max. 30-40kW power available on the market. These emit a fixed number of pulses via an electrical contact per kilowatt-hour consumed. You can connect up to 2 of these meters to the S0 inputs of the cFos Power Brain Controller in order to record and display the current power and consumption or to use them for load management.
For more information on S0 meters, see our documentation page on this topic.

No. If you do not install a meter at all, the cFos Charging Manager makes default assumptions: The existing power allocated for charging cars is then simply divided by the number of cars currently charging. It is then assumed that each car always consumes the maximum power that has just been allocated. The use of the phases is adjustable here, but fixed.
For single-phase charging cars, you can install the EVSEs out of phase and configure the Charging Manager accordingly. Then, for example, with 11kW (3 x 16A) total power, the cFos Charging Manager can provide 16 A each to two cars charging at the same time

The cFos Power Brain Controller supports secure SSL encryption for OCPP, the web interface and the HTTP API. Additionally, you can import SSL certificates to authenticate your communication partner. This will prevent anyone from misusing your EVSE to modify data (e.g. charging currents)
Software updates from cFos Power Brain Controller are also secure. The corresponding firmware is digitally signed by us. This means that a firmware update can only be performed with authentic firmware

Yes. The cFos Power Brain Controller has a Modbus RTU and TCP interface. You control the EVSE by setting the corresponding Modbus registers. If you do not have Modbus support in your automation software, you can also read and set the Modbus registers through the HTTP API. Here you will find a description of the HTTP API. The charging current is specified in 0.1A steps. Since the cFos Power Brain Controller has WLAN, you do not need any additional network cabling.

OCPP is a standard protocol specially developed for EVSEs. With OCPP a world opens up: You can use OCPP for example
  • Make the status of your EVSE visible to yourself and others on the Internet. So you can see if it is currently occupied, if someone is loading, etc.
  • Connect your EVSE to backends for billing purposes. This allows you to integrate your EVSE into the networks of large charging station operators and earn money with your EVSE and/or conveniently bill it if several people use it
  • Integrate your EVSE into a load management system. Thanks to cFos Charging Manager, we offer a load management system that can also be used by EVSEs without OCPP. However, most other providers require OCPP.
The cFos Power Brain Wallbox is (as of September 2021) the most affordable EVSE with a mature and comprehensive OCPP 1.6 implementation, including various professional features.

As of November 2020, we are not aware of any support for the cFos Power Brain Controller in OpenWB. However, since the cFos Power Brain Controller can be conveniently controlled remotely via an HTTP API, we assume that support will come soon. Here are links to our Modbus and HTTP API documentation:
Documentation Modbus register
Documentation HTTP API

The following options are available here:
  • You can connect other Modbus devices supported by us to the interface and read and remotely control them
  • You can connect the Tesla Wall Connector Gen 2
  • You can remote control the cFos Power Brain Controller via Modbus RTU. However, this is only recommended if there is appropriate wiring anyway. Otherwise, we recommend Modbus TCP, HTTP or OCPP via WLAN

To do this, you must use the Charging Manager. In the web interface, click on "Configuration" in the menu. First set the available total power for all EVSEes under "Max. Total Power", set the available total power for all EVSE. Under "Power Reserve" you should set a reserve that is not touched so that the fuse does not blow in the event of an overload. If you have a private household, we recommend 2500W as a reserve. Under "Max Total EVSE Power" you can enter the maximum power for which the supply line to your EVSEes is designed, if this is the limiting factor. Otherwise enter 0 there.

By default, one EVSE is set up, namely the cFos Power Brain Wallbox with address "localhost". With localhost, the Charging Manager addresses its own devices. If you now add another EVSE, e.g. a cFos Power Brain Wallbox, you must enter the IP address it has in your network as the address, e.g. 192.168.2.102:4701. If the EVSE to be connected is addressed via RS 485 interface, enter COM1,baudrate,8,n,1 here.

The Charging Manager distributes the available charging power among the configured and currently charging EVSEs (load management).

The cFos Charging Manager polls all configured devices for their status every few seconds. Since several devices can be addressed simultaneously via IP and only all devices one after the other with a two-wire connection, we recommend IP connections. Then the Charging Manager can react more quickly

In this case, the Charging Manager assumes that the EVSE is drawing maximum power and reports errors in the overview. It is OK if the connection is interrupted for a few seconds in between. However, you should otherwise ensure stable and reliable connections. In Modbus mode, the EVSE has a fail-safe, i.e. if no more Modbus communication is received for an adjustable number of seconds, the EVSE switches off automatically or to an adjustable minimum charging current. With OCPP, you can also achieve this behaviour by means of "Charging Profiles".

The cFos Power Brain Wallbox has an IP65 housing. As long as you also make sure that it does not rain into the plug of the charging cable (has a protective cap), you should be able to install the EVSE outdoors without any problems.

As of September 2021, German and English are supported. Other languages could be added if there is a demand for them.

Access restriction works via the web interface, via RFID and via the app. However, you can also have an electrician retrofit a key switch with simple steps. The CP signal, i.e. the orange wire, must then be routed via the key switch. When the switch is open, the cFos Power Brain Controller does not notice that a car is plugged in and therefore does not release the charge. The warranty remains intact even with such a modification.

With a cable length of approx. 15m, 5 x 2.5 mm² are sufficient for the 11kW EVSE, for the 22kW EVSE it is better to use 5 x 4 mm². The 11kW EVSE must be fused with 16A for all phases, the 22kW EVSE with 32A. But: The EVSE may only be installed by a qualified specialist who must know which wire cross-sections and fuses are required. Unlike a cooker, instantaneous water heater and other household appliances, an EVSE is a permanent consumer and is therefore subject to stricter safety requirements. Therefore, please do not install it yourself, but always call in a specialist.

No. The EVSEs must be wired in a star configuration starting from a distributor and each must be protected with a type A RCD and circuit breaker. The DC residual current sensor built into the cFos Power Brain Wallbox reacts at 6mA residual current (direct current). If you were to connect several EVSEs in series, they could each deliver less than 6mA residual current but more than 6mA in total. This would then not be detected. Therefore, this series connection is not permitted.

You can interrupt the orange-coloured line of the charging cable (CP signal) that goes to the cFos Power Brain Controller using a key switch. With a round-trip receiver, you need a potential-free relay contact that is opened when the EVSE is not allowed to charge. The controller will then no longer recognise that a car is plugged in and will not enable charging. It is not recommended to use a key switch to interrupt the power supply to the EVSE or the controller.
To control the charging power, you can set a charging rule for each EVSE that becomes active when a potential-free input is switched. Here you can then specify a certain power or a percentage of the power, see Charging rules

cFos Power Brain Controllers from Rev. 1.1 (recognisable by the bent pin header) have a 330 Ohm resistor at the LED output (3.3V). Any LED that is designed for a current of more than 5 mA can be connected there. cFos Power Brain Controllers of Rev. 1.0 (the pin header is not accessible without opening the Power Brain housing) do not have a resistor. Here, any LED with the appropriate series resistor can be connected to the LED output (3.3V)

The tiles on the start page show the consumed kWh of the EVSE, as well as the imported and exported energy of the meters. In addition, you can download a transaction log under "Configuration" in which all charging processes are logged with kWh. If you set up individual users, they can also download their transaction log. The transaction logs are CSV files that you can process in Excel, for example.

Under "System Configuration" -> Files there is a button for resetting the cFos Charging Manager configuration or the entire system.

If the cFos Power Brain Wallbox has lost the connection to the WLAN, you can first restart your router or access point. If this does not help, you can disconnect the EVSE from the power supply for a few seconds. After the restart, it should log back into the WLAN. If this does not happen after a few minutes, the cFos Power Brain Wallbox will automatically start its own Wi-Fi access point so that you can use it to connect to the EVSE and check the configuration.

Under "Configuration" -> "Modbus Test" you can describe a register with a desired value for the kWh of the meter. The address of the meter is localhost: 4702 for S0 meter 1 or localhost:4703 for S0 meter 2. The slave Id is 2 for S0 meter 1 and 3 for S0 meter 2. Enter 8058 as the register, type "64 bit qword", number 1, value to be written the desired meter reading in Wh. Then click on "Write".

After you have set the maximum house connection power in the Charging Manager settings, you can measure in two ways
  • You install one or more consumption meters (for consumption without EVSE) and generation meters (or read your solar inverters). The Charging Manager then calculates the power available for charging the electric cars as the house connection power minus the consumption meter plus the generation meter. If you do not install a meter, the Charging Manager will divide the house connection power among the charging EVSEs. If you do not want to measure the house consumption, you can configure the house connection power lower according to the maximum house consumption (static)
  • You install a grid reference meter. This measures the power that flows through your house connection, including all consumers, generators and EVSEs. However, you must then install at least one meter that measures the consumption of the EVSE. The load management of the Charging Manager then calculates the charging power for the electric cars as the house connection power minus the difference between the mains supply and the EVSE. In other words, it subtracts the EVSE power from the grid supply to determine how much energy is consumed or generated elsewhere. Typically, a meter is assigned to each EVSE. However, you can also connect all EVSE to one meter and thus possibly save meters if you do not need individual metering for the EVSE (for billing purposes). If you have a generation source (PV system), you need a bidirectional meter as a grid reference meter to be able to distinguish between purchase and feed-in
You tell the Charging Manager which function the installed meters have by specifying the role of the meter in the meter configuration.

In Germany, all meters used for billing purposes must be "calibrated". This calibration is carried out in the EU by means of MID certification. A MID-compliant meter is therefore suitable for billing purposes.

There is no special obligation to do this in a private environment. In a commercial environment, you must have the EVSE checked annually by an electrician.

Under "Configuration" -> Firmware update, you can check for new versions and install them by clicking on "Update now". The EVSE will then restart.

The 12V of the S0 terminal may be loaded with a maximum of 25 mA. They are actually only used to supply a voltage for possible S0 meters or switching contacts. For each S0 meter and contact that you supply with this 12V, you still have to subtract 5 mA each. This means that only 20 mA or 15 mA are available.

The LED of the cFos Power Brain Controller flashes in a pattern that repeats every 3 seconds. represents an illuminated LED and a non-illuminated LED in the following explanation.
Standby (LED off)
VehicleDetected (LED flashes briefly every 3 seconds)
Charging (LED flashes: 1.5 seconds on, 1.5 seconds off)
ChargingVentilation (LED flashes: 1 second on, 2 seconds off)
NoPower (LED flashes four times)
Error (LED flashes twice with a pulse of 2)