Frequently asked questions


Yes, there is a charging rule that allows you to configure that charging should only take place if the solar power system delivers a certain minimum power. The cFos Charging Manager can read generation counters, SMA inverters and inverters that support SUNSPEC. More will follow. You can also test yourself whether the Charging Manager already supports your solar installation.

There is a charging rule in the integrated Charging Manager with which you can set that the electric car should only be charged from a certain solar power. In addition, you can set in different variations the power with which charging should then be carried out. The cFos Charging Manager also supports excess solar charging.

What we currently do not support is the automatic switch-on and switch-off of individual phases if the solar power 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 kit for the cFos Power Brain Wallbox. But that won't 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 Charging 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 Charging 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 EVSE 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.

You can simply install 2 or more cFos Power Brain wallboxes. One is then the charging manager / master (the cFos Charging Manager is integrated in the cFos Power Brain Controller) and the other "slaves". Then, for example, set 11kW or more as the house connection power and the power will be dynamically divided depending on whether 1 or 2 cars are charging. In other words, as long as several or different phases are not actually being charged, the charging car receives full power.
You can also connect an intermediate meter that measures the electricity consumption of your house (without EVSEs). In this way, you could make the entire house connection service available to the store when it is not needed in the house.

Not at the moment, but it is a work in progress.

Yes. The Tesla Wall Connector Gen 2 has an RS485 two-wire interface that allows it to be remotely controlled as a slave.

Attention: The newer Tesla Wall Connector Gen 3 cannot be remotely controlled at present.
Tesla is planning 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 Charging Controller; then you can set up Tesla Wall Boxes in the cFos Charging Controller under "Charge Management" Tesla Wall Boxes. Our integrated Charging Manager can then dynamically distribute the available charging power to all charging stations
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 Charging Controller has a web interface that allows you to enable charging and set the maximum charge current. You can access the cFos Charging Controller's hotspot from your computer and cell phone using your browser. Alternatively, you can also connect the cFos Charging Controller to your home network via WLAN and then access the Web interface from your home network

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 EVSEs 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 Charging 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 delivered with an S0 meter. In the trade there are also inexpensive intermediate meters with a maximum output of 30-40kW. Via an electrical contact, these output a set number of pulses 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 it for charge 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 Charging 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 Charging 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 EVSE into a charging management system. We offer a charge management system that can also use EVSEs 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 Charging Controller in OpenWB. However, since the cFos Charging 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 Charging 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 EVSE with address "localhost". With localhost, the Charging Manager addresses its own devices. If you now add another EVSE, e.g. a cFos EVSE, 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 distributes the available charging power to the configured and currently charging EVSEs.

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.

The cFos EVSE has an IP67 housing. As long as you also make sure that it doesn't rain into the plug of the charging cable (has a protective cap), you should be able to mount the EVSE 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 currently works via the web interface and later via an app. However, you can have a key switch retrofitted by the electrician 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 Charging Controller does not notice that a car is plugged in and disables charging. 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, 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 EVSE 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-coloured line of the charging cable that goes to the cFos Charging 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 interrupt the power supply to the EVSE or the controller by means of a key switch
To control the charging power, you can set a charging control 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. There will be further refinements here in the future as part of a software update.

cFos Charging 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 Charging 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)

Under "System configuration" -> Modbus you can write 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 counter reading in Wh. Then click on" Write ".

The LED on the cFos Powerbrain 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 in double cycle with 2 pulse)