Frequently asked questions


Yes. There is a charging rule that you can use to configure that charging should only take place when the solar system delivers a certain minimum output. The cFos Charging Manager also masterssolar excess charging. For this purpose, the cFos Charging Manager can read out production meters and/or access the inverters of the solar system directly. For example, many inverters from SMA 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 currently do not support is the automatic switching on and off of individual phases when the solar output drops below 4200 W. To do this, we would have to be able to switch the phases individually using separate contactors. We are considering providing a retrofit or conversion kit for the cFos Power Brain wallbox. But that 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) that are used to protect the supply lines to the wallbox (but not the ones 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 in 1, 2 and 3 phases. However, your energy supplier and the VDE stipulate that all phases must be loaded as evenly as possible. Individual phases may differ from the others in terms of output by a maximum of 4.5 kW. If you have several cars that do not charge 3-phase, 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 which phases the power is drawn on and can take this into account accordingly.

In standby and with the car plugged in, it consumes less than 1.5W. While a car is being charged, the EVSE, including the relay and contactor, needs 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. You only need to lay an additional twisted two-wire connection if you also want to address devices that require cabling via RS 485 (e.g. for the ABB B23 / B24 or Eastron Modbus meters, EVSE controllers from EVRacing, Tesla Wall Connector Gen. 2). If you want to connect up to 2 S0 meters, you need a twisted two-wire cable for each meter.

If you operate a single cFos Power Brain wallbox, it charges with 16A (11kW) or 32A (22kW) without any further configuration, depending on the model. As long as you do not want to use any other capabilities, you do not need to configure any Charging Manager options. If you want to operate several cFos Power Brain wallboxes and/or third-party boxes on one connection, you must configure the cFos Charging Manager if the simultaneous charging on all EVSEs overbooks your house connection service.

You can easily install 2 or more cFos Power Brain Wallboxes. One is then the load manager, ie master (the cFos Charging Manager is already integrated in the cFos Power Brain Controller) and the other(s) "slaves". Then you set, for example, 11kW or more as the house connection power and the power is divided dynamically depending on whether 1 or 2 cars are charging. In other words, as long as there aren't really charging in several phases or in different phases, the charging car gets full power.
You can also connect an intermediate meter that measures the power consumption of your house (without wall boxes). In this way, you could make the entire house connection available to the store when it is not 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.

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

You can use the RS485 interface to connect several Tesla Wall Connectors Gen 2 to a bus and connect them to the RS485 interface of the cFos Power Brain Controller; then you can set up Tesla Wallboxes 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: With newer Tesla Wall Connector Gen 2, the cFos Power Brain controller can also evaluate and display the charging current actually used and the total kWh consumed.

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 the 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 settings of the EVSE. The maximum charging current is then effectively signaled to the car in approx. 1% steps. So you are in full control. When 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 values 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 "Charge" under the menu item "cFos Power Brain Configuration" and deactivate the EVSE, ie turn off both switches. Now wait 30 seconds and switch both on again.

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 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 comes with an S0 counter. In the trade there are also inexpensive intermediate meters up to a maximum of 30-40kW output. These emit a specified number of pulses per kilowatt hour consumed via an electrical contact. You can connect up to 2 of these counters to the S0 inputs of the cFos Power Brain Controller in order to record and display the current performance and consumption or to use it for load management.
For more information on S0 counters, see our documentation page on the subject.

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 appropriate Modbus register. If you do not have Modbus support in your automation software, you can also read and set the Modbus registers using the HTTP API. Here you can find a description of the HTTP API. The charging current is given 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 wall box into a load management system. Thanks to cFos Charging Manager, we offer load management that can also use wall boxes without OCPP. However, most other providers require OCPP.
The cFos Power Brain wallbox is (as of September 2021) the cheapest EVSE with a mature and extensive 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 for this will be available soon. Here are links to our Modbus and HTTP API documentation:
Documentation Modbus Registers
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 have to use the Charging Manager. In the web interface, click on "Configuration" in the menu. First set the total power available for all EVSEs under "Max. Total Power". Under "Power Reserve" you should set a reserve that is not touched so that the fuse does not trip 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 EVSEs 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. If the EVSE to be connected is addressed via RS 485 interface, enter COM1,baudrate,8,n,1 here.

The Charging Manager divides the available charging power between the configured and currently charging wall boxes (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 lost for a few seconds in between. Otherwise, however, you should ensure stable and reliable connections. In Modbus mode, the EVSE is fail-safe, ie if no more Modbus communication has been received within an adjustable number of seconds, the EVSE switches off automatically or to an adjustable minimum charge current. With OCPP you can also achieve this behavior using "Charging Profiles".

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

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

The access restriction works via the web interface, via RFID and via the app. However, you can also have a key switch retrofitted by an electrician in a few simple steps. The CP signal, ie the orange line, 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 accordingly does not enable charging. The guarantee 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, but 5 x 4 mm² should be used for the 22kW EVSE. 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 needs to know which wire cross-sections and fuses are required. In contrast to stoves, water heaters and other household appliances, a EVSE is a permanent consumer and is therefore subject to more stringent security requirements. Therefore, please do not install it yourself, but always consult a specialist.

No. The wall boxes must be cabled from a distributor in a star shape and each protected with a type A FI and circuit breaker. The DC fault current sensor built into the cFos Power Brain wallbox reacts to 6 mA fault current (direct current). If you were to connect several wallboxes in series, they could each deliver less than 6mA fault current but more than 6mA in total. This would then not be recognized. This series connection is therefore not permitted.

You can interrupt the orange line of the charging cable (CP signal) that goes to the cFos Power Brain Controller using the key switch. With a ripple control receiver, you need a potential-free relay contact that opens when the wallbox is not allowed to charge. The controller then no longer recognizes that a car is plugged in and does not enable charging. It is not recommended to use a key switch to interrupt the power supply to the wallbox or the controller.
To control the charging power, you can set a charging rule for each wall box 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 home page show the kWh consumed by the EVSEs and the imported and exported energy from the meters. In addition, you can download a transaction log under "Configuration" in which all charging processes are recorded 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 to reset 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 turn off the power to the EVSE for a few seconds. It should log into the WLAN again after the restart. If this does not succeed after a few minutes, the cFos Power Brain wallbox automatically starts its own WLAN access point so that you can use it to dial into the EVSE and check the configuration.

Under "Configuration" -> "Modbus Test" you can write a register with a desired value for the kWh of the meter. The address of the counter is localhost: 4702 for S0 counter 1 or localhost: 4703 for S0 counter 2. The slave ID is 2 for S0 counter 1 and 3 for S0 counter 2. Enter 8058 as the register, type " 64 bit qword ", number 1, value to be written the desired counter 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 wall boxes) and production meters (or read your solar inverters). The Charging Manager then calculates the power available for charging the electric cars as house connection power minus the consumption meter plus the generation meter. If you don't install a meter, the Charging Manager divides the house connection power between the charging wall boxes. 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 reference meter. This measures the power that flows through your house connection, including all consumers, producers and wall boxes. But then you have to install at least one meter that measures the consumption of the wall boxes. 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 purchased electricity and the wall boxes. In other words, it subtracts the output of the wall boxes from the grid purchase in order to determine how much energy is otherwise consumed or generated. A meter is typically assigned to each wall box. However, you can also attach all wall boxes to one meter and thus possibly save meters if you do not need individual recording for the wall boxes (for billing purposes). If you have a generation source (PV system), you need a bidirectional meter as a purchased electricity meter in order to be able to distinguish between import and feed-in.
You tell the charging manager what 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 takes place 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 import them by clicking on "Update now". The wallbox then restarts.

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

The LED of the cFos Powerbrain flashes in a pattern that repeats every 3 seconds. In the following explanation, represents a lit and a non-lit LED.
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 double pulse)