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 when a certain amount of solar power is available. In addition, you can set in different variations the power with which charging should then be carried out. Here we can easily retrofit other variants for optimal use of the available power.

What we do not currently support is the automatic switching on and off of individual phases when the solar power drops below 4200 W. We would have to use separate contactors for this. For 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 EVSE. However, this will not be feasible before Q3 2021.

Here's 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 Charging Controller is protected). However, you may not switch individual phases on or off during the charging process

The cFos Charging Controller can charge electric cars in 1, 2, and 3 phases. However, your power supplier and VDE stipulate that all phases must be loaded as evenly as possible. Individual phases may differ from each other in power by a maximum of 4.5kW. If you have several cars, which do not charge 3-phase, have your electrician connect the EVSEs, so that all phases are turned in comparison to other EVSEs

In standby and with car plugged in, it consumes less than 1.5W. While a car is charging, the EVSE including relay and contactor needs about 8W.
Our EVSE has a 10A power switch. If you do not use the cFos Charging Controller for a longer period of time, you can use it to switch it off

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 wiring) that can be addressed via IP. Only if you want to address additional devices that require a cabling via RS 485, you have to install an additional twisted pair connection (e.g. for the ABB B23 / B24 or Eastron Modbus meter, EVSE controller from EVRacing, Tesla Wall Connector Gen. 2). If you want to connect up to 2 S0 meters, you need a twisted pair cable for each meter.

You can simply install 2 or more cFos EVSEs. One is then the Charging Manager (cFos Charging Manager is integrated into the cFos Charging Controller) and the other(s) is(are) "slave(s)". Then, for example, set 11kW as the house connection power and the power will be dynamically distributed depending on whether 1 or 2 cars are charging. I.e. as long as there are not really more than one charging car, the charging car gets the full 11kW.
You can additionally connect an intermediate meter which measures the power consumption of your house (without EVSEs). This way you could provide additional power for charging when it is not needed in the house

Not currently, but this is planned for the near future

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 Charging Controller can also evaluate and display the actual charging currents and the total kWh consumed.

See the description of cFos Charging Manager (integrated into cFos Charging Controller or available as a software solution for Windows and Raspberry Pi) for a list of currently supported EVSEs. We plan to expand this list significantly in the near future. In addition, all EVSEs with 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.

We have no experience with cars put into standby mode yet. Therefore, we are currently gathering empirical data in order to support such a function in the future under certain circumstances.

We recommend to test if a car in standby mode "wakes up" if they under the menu item "cFos EVSE configuration" first "disable charging" and then disable the EVSE, i.e. turn 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 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

In the beginning, our software might have teething troubles, so you might want to install software updates or send us log files. Hence our requirement for an Internet connection

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

In the trade there are inexpensive intermediate meters up to max. 30-40kW power. These give out a fixed number of pulses per kilowatt hour consumed via an electrical contact. You can connect up to 2 of these meters to the S0 inputs of the cFos Charging Controller to record and display current power and consumption or use them 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 Charging Controller has a Modbus RTU and TCP interface. You control the EVSE by setting the appropriate Modbus registers. They can also be set by the HTTP API. Here you can find a description of the HTTP API. The charge current is given in 0.1A steps. Since the cFos Charging 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 EVSE is (as of November 2020) by far the cheapest EVSE that supports OCPP

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 must use the Charging Manager. In the web interface, click on "Configuration" in the menu. First set the available power under "Max. Total Power" set the available total power for all EVSEs. 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 4500W as a reserve. If only the EVSEs are connected, 2500W should be sufficient. 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 EVSEs, provided they are actually plugged in and charging.

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.

Yes. Our first software update contains German dialogues. After commissioning your cFos EVSE, you can install this software update.

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. The EVSE must be fused with 16A for all phases. But: The EVSE may only be installed by a qualified specialist who must know which wire cross-sections and fuses are required. In contrast to the cooker, instantaneous water heater and other appliances in the household, a EVSE is a permanent consumer and is therefore subject to more stringent safety requirements. Therefore, please do not install it yourself, but always call in a specialist.

No. To operate 2 x 11kW EVSEs, you need to have a 22kW line laid so that both can draw their 11kW. Then you need a "junction box" from which you branch off the individual EVSEs. Here, each EVSE must be fused with 11kW (16A). The supply lines from the branching point then only need to be designed for 11kW (16A).
It is also best to ask your electrician. He is very familiar with the exact regulations and often has an optimal wiring solution that fits your specific case well.

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)

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)