If your wallbox is only charging on one phase, there can be several reasons for this. Please go through the following points in order—from the simplest to the most complex.
1. App settings
Check phase configuration: Is the wallbox set to 3 phases in the app? An incorrect basic configuration will result in single-phase charging.
Automatic phase switching & PV surplus: Is the wallbox set to automatic phase switching? Three-phase charging requires at least approx. 4.1 kW of PV surplus. If there is less surplus, the system automatically switches to single-phase (starting from approx. 1.4 kW) to prevent the charging session from aborting. → Check the current PV surplus in the app.
Manual mode active? Check if a manual charging mode with a fixed single-phase setting has been accidentally activated.
2. Charging cable check
Cable type: Type 2 charging cables are available in single-phase and three-phase versions. With a single-phase cable, the lower pins in the connector are "empty." Check the label or the data sheet:
- "3.7 kW" or "7.4 kW single-phase" → single-phase cable
- "11 kW" or "22 kW" → three-phase cable (required for 3-phase charging)
Extension or adapter cables: If a three-phase charging cable is combined with a single-phase extension, the vehicle will only charge on one phase. Remove all adapters and extensions and test again.
Cable defect: Loose connections, damaged wires, or oxidized contacts can interrupt individual phases. As a test, connect a different, verified three-phase cable. If the wallbox charges on three phases with the new cable, the original cable is defective.
3. Vehicle-side causes
Hybrid vehicles (PHEV): Plug-in hybrids can generally only charge on one phase, most with a maximum of 3.7 kW. This is not a fault, but a hardware characteristic of the vehicle. Examples: Opel Astra PHEV, Kia Niro PHEV, Mitsubishi Outlander PHEV, and many BMW, Mercedes, and VW hybrids.
Single-phase onboard charger (OBC) in EVs: Some fully electric vehicles also have a single-phase OBC, e.g., Opel Corsa-e or Mazda MX-30. In this case, the vehicle will only charge on one phase by design, regardless of the wallbox and cable. Check the OBC specification in the vehicle manual or data sheet.
4. Home installation & fuses
Check fuses (circuit breakers): Are all three phase fuses for the wallbox switched on in the distribution box? A tripped circuit breaker on one phase will result in only 1–2 phases delivering power.
Residual Current Device (RCD): Is the RCD for the wallbox switched on and not tripped?
Connection at the wallbox: Some wallboxes are intentionally wired for single-phase use only. A typical case for self-installation: Only L1, N, and PE were connected. → This can only be determined by a visual inspection of the opened device by a qualified electrician.
Grid type / home connection: A three-phase wallbox requires a 400 V three-phase power connection. With a standard 230 V connection, three-phase charging is physically impossible.
5. Wallbox configuration
Internal phase configuration: Check the wallbox configuration menu (web interface, manufacturer app, DIP switches): Is the wallbox internally configured for 3-phase operation? Some models have a switch or parameter that toggles between 1-phase and 3-phase operation.
Is the firmware up to date? Outdated firmware can cause errors in phase switching. Check the software version, install updates, and reset the wallbox if necessary.
6. Hardware defect of the wallbox
If all the points above have been ruled out, there may be a defect in the wallbox (e.g., a defective phase contactor). In that case:
- Contact your installer to measure the voltages per phase (only to be performed by a qualified electrician, working in a de-energized state).
- Contact the wallbox manufacturer (log files / diagnostics / replacement).