Victron battery settings
Victron battery settings for Reduxi: ESS settings, Modbus TCP and unit ID on the GX device.
1 Technical documentation
Victron documents for the Modbus TCP connection and the ESS settings:
- Modbus-TCP register list (XLSX) – Register list. The Unit ID mapping tab shows which unit ID belongs to which device.
- Data communication with Victron Energy products (PDF) – Whitepaper with the Modbus-TCP section.
- Modbus-TCP FAQ – How to enable Modbus-TCP on a GX device.
- Energy Storage System (ESS) manual – Description of the ESS settings in the GX device.
2 Required equipment
You need:
- Victron GX device with the Victron battery system connected
- Reduxi Controller
- Network connection (Ethernet) between the GX device, the Reduxi Controller and your router
- Laptop or tablet with internet access to configure the device in Reduxi
3 Settings on the Victron GX device
Make these settings in the menu of the GX device. The screenshots show the Remote Console of the GX device.
3.1 ESS settings
Open Settings – ESS. Under Grid metering, select Inverter/Charger and confirm.
The screenshots show these ESS values:
| Setting | Value |
|---|---|
| Mode | Optimized (without BatteryLife) |
| Grid metering | Inverter/Charger |
| Multiphase regulation | Individual phase |
| Minimum SOC (unless grid fails) | 30% |
| Limit inverter power | Off |
| Grid setpoint | 20 W |
3.2 Enable Modbus TCP and read the unit ID
Open the Device List and select Settings.
Select Services.
Set Modbus TCP to Enabled. Then open the Modbus TCP entry.
Select Available services.
Under Available services you see the connected devices with their unit IDs. You need the unit ID of the battery later in Reduxi as the Modbus address.
| Service | Unit ID in the screenshot |
|---|---|
BMS-Active (com.victronenergy.battery) |
225 |
EV Charging Station (com.victronenergy.evcharger) |
40 |
Grid meter (com.victronenergy.grid) |
31 |
4 Log in to the Reduxi web interface
You can open the Reduxi web interface in two ways:
http://reduxi.local. You can find the controller's IP address in your router's device list or in the Reduxi app under Reduxi devices.admin · Password: admin (factory default)5 Add the Victron battery to Reduxi
Use these steps to add the battery or to edit an existing device.
5.1 Basic settings
Log in locally to the Reduxi Configurator on the controller (see Point 4) and click + Add device.
In the first step (basic settings), select the device type and type of the Victron battery and enter a name of your choice. Then press Next.
5.2 Communication settings
Enter the connection details of the GX device:
| Parameter | Value |
|---|---|
| Connection | TCP/IP |
| IP | IP address of the Victron GX device |
| Port |
502 (standard Modbus TCP port) |
| Modbus address | Unit ID of the battery, read under Available services (see Point 3) |
5.3 Test communication
Click Test communication at the bottom of the wizard. It reads the Victron battery once and saves nothing. If the test succeeds, click Done: only Done creates the device.
6 Check the readings
6.1 Last measurements
After communication is established, check the values of the battery under Devices in the Reduxi Configurator.
6.2 Enable control by Reduxi
For control by Reduxi, set the control type of the device to AUTO under Devices in the Reduxi Configurator. Only then do strategy commands affect the battery.
To reduce energy costs with dynamic prices and dynamic tariffs, define a strategy as described in Strategies for Reduxi controller.
✓ Summary
Preparation (Points 1–2): Open the Victron documents and prepare the GX device, the Reduxi Controller and a laptop.
Victron GX device (Point 3): Set Grid metering to Inverter/Charger, enable Modbus TCP and read the unit ID of the battery.
Add to Reduxi (Points 4–5): Log in to the Reduxi web interface, add the device and enter IP, port 502 and unit ID.
Go live (Point 6): Check the readings and set the control type to AUTO.
→ Common issues
| Issue | Solution |
|---|---|
| Test communication fails | Check that Modbus TCP is Enabled under Settings – Services on the GX device. Check the IP address of the GX device, port 502 and the unit ID under Available services. |
| The Modbus/TCP page on the GX device shows an error | The page shows the error and the time of the last error. Press Clear error and run the test again. |
| Open configurator does not open or stays empty | The tunnel is not active yet. Wait about 30 seconds and check that the controller is online. |
Login with admin is rejected |
The password was changed during installation. Ask the installer. The Reduxi account password does not work here. |
reduxi.local does not load |
Your device is not in the same network as the controller. Use the IP address or the tunnel connection. |
| Communication test fails, device shows offline | Check reachability, IP address / port / unit ID, and that the protocol is enabled on the device. |