How to connect Victron Energy MultiPlus II battery with Reduxi controller
Connect a Victron Energy MultiPlus-II to the Reduxi Controller.
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Product photo of a blue Victron Energy MultiPlus-II inverter/charger on a white background, front view, with black plastic corner caps at the top and bottom and a dark grey base at the bottom. Front: 'victron energy BLUE POWER' logo at the top left; an orange stripe with 'www.victronenergy.com'; model text 'MultiPlus-II' with '12 | 3000 | 120' and a line about AC transfer switch and capacity 50 A (small print); a QR code at the right; warning symbols and 'IP21'. LED panel at the left labelled 'charger' (mains on, bulk, absorption, float) and 'inverter' (inverter on, overload, low battery, temperature); 'inverter on' LED is green, the others are off. A small wiring diagram and several lines of warning text in French and English (small print) at the right.
1 Technical documentation
Instructions for connecting and configuring the device are on the Victron web page.
- Victron manuals: MultiPlus-II – Manufacturer instructions. Select the product in the drop-down list.
- MultiPlus-II 230V manual (PDF) – Installation, wiring and VE.Bus connection.
- MultiPlus-II datasheet (PDF) – Models, specifications and accessories.
- Victron Modbus-TCP FAQ – Enable Modbus-TCP on a GX device and find the unit IDs.
- MultiPlus-II product page – Product description and downloads.
2 Required equipment
- Victron Energy MultiPlus-II
- GX device of the Victron system (acts as the Modbus-TCP gateway)
- Reduxi Controller
- Network connection between the GX device and the Reduxi Controller
- Laptop or tablet with internet access to configure the device in Reduxi
3 Configure the Victron system
3.1 Enable Modbus-TCP on the GX device
Modbus-TCP is disabled by default on a GX device. To enable it, go to Settings – Services on the GX device, scroll down and enable the Modbus-TCP service.
4 Log in to the Reduxi web interface
You can open the Reduxi web interface in two ways:
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Screenshot of three Reduxi mobile app screens side by side, with cyan boxes and number badges 2 to 4. Left screen (dashboard, dark theme): menu icon at top left marked with a box and badge 2; 'reduxi' logo; tabs 'Real time data' (active) and 'Statistics'; price 5.79 € and temperature 3.2 °C; energy flow diagram with a house in the centre (-1.25 kW) and icons with values 69.0 W, 1.3 kW, 1.1 kW (red ring), -165.0 W with 97 % (red ring) and 0.0 W values at the bottom; tabs 'Power' and 'Energy'; bottom navigation: Dashboard, Diagnostics, Device control, Settings. Middle screen (side menu): 'reduxi' logo, 'Number of locations: 1233', heading 'Reduxi device management', entries '+ Add Reduxi location' and 'Reduxi devices' (marked with a box and badge 3), then 'My profile' and 'About app'. Right screen (device page): Back; picture of a black Reduxi controller with two Ethernet ports; status 'Connected'; card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'; card 'Connect to configurator': 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' with button 'Activate tunnel connection' (marked with a box and badge 4); card 'Unit details' with field 'Unit ID'.
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Screenshot made of two parts side by side. Left part: Reduxi mobile app screen on a dark background. Top: Back button; picture of a black Reduxi controller with two Ethernet ports and a terminal block; status 'Connected' with a Wi-Fi icon. Card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'. Card 'Connect to configurator' with a key icon: 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' and button 'Open configurator', marked with a cyan box and number badge 5. Below: card 'Unit details' with a field 'Unit ID' (value not visible). Right part: Reduxi Configurator opened in a browser, marked with a cyan frame and number badge 6. Header: back arrow, 'Tunnel connection', reload icon. Left sidebar with icons (lightning, chip, lightning bolt, bar chart, gear). Page 'Home' with a green link icon. Green notice: 'New patch available. Click here to apply.' with a close X. Time 09:12:56. Energy flow diagram with a house in the centre (1.700 kW) and icons for grid (0.000 kW), solar (1.700 kW), battery (green, 0.000 kW and 0.800 kW), a device at left (0.900 kW), electric vehicle and a charger or device at bottom. Label 'Energy manager' at the bottom.
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)Text description of this image
Screenshot of the Reduxi Configurator login page in a Chrome browser window. The address bar shows 'Not secure' and 'reduxi.local'; the address bar is marked with a cyan box and an enlarged copy of it (cyan box, text 'Not secure reduxi.local') is shown at the left, connected by a cyan line. Page background: light grey line drawing of a house with solar panels (green), a wall box, an inverter, a car and a charger. Top left: 'reduxi configurator' logo. Login box in the centre with title 'Login', a language selector (English flag, 'English'), a username field and a password field, and a dark 'Login' button.
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Screenshot of the Reduxi Configurator web interface after login, light theme. Top left: 'reduxi configurator' logo. Header bar: 'Home' at left, green 'Connected' status at top right. Left sidebar: expanded section 'Devices' with a list of entries, then collapsed sections 'Manager' and 'Configuration' and 'Settings'. Main area: energy flow diagram. House in the centre with ring, value 24.20 kW. Grid icon at top left, 24.20 kW (red dot on its line). Solar icon at top right, value '-'. Left icon (battery or device), 6.700 kW (green dot on its line). Right icons (battery storage and a device), values '-'. EV charger icon at bottom left, 31.00 kW. A further device icon at bottom right. Label 'Energy manager' below the house.
5 Add the MultiPlus II to Reduxi
Use these steps to add a new device or to edit an existing one.
5.1 Basic settings
Log in to the Reduxi Configurator via the browser (see Point 4). Click + Add device.
Enter the basic settings of the device.
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Screenshot of the Reduxi Configurator page 'Basic settings'. Device type *: Battery (dropdown). Type *: Victron Energy MultiPlus II (dropdown). Name *: Victron Energy MultiPlus II (text field). Buttons: Back (bottom left), Next (bottom right, dark).
5.2 Communication settings
Select the communication channel of the device.
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Screenshot of the Reduxi Configurator page 'Communication channel and device configuration'. Connection *: TCP/IP (dropdown). IP *: 192.168.1.1 (field is active, text cursor at the end). Port *: 502. Buttons: Back (bottom left), Test communication and Next (bottom right, Next is dark).
5.3 Advanced settings
Choose and enter the advanced settings:
| Parameter | Value |
|---|---|
| Reading delay | 250 |
| Writing delay | 250 |
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Screenshot of the Reduxi Configurator dialog titled "Advance settings" (as shown). Toggles, each with a question: Do you want to set data saving interval: No (hint: Default: 1 min). Do you want to set reading delay: Yes, value field 250 with unit ms. Do you want to set writing delay: Yes, value field 250 with unit ms (the field is active and the value is highlighted). Do you want to set maximum export power: No. Do you want to set maximum import power: No. Do you want to invert direction for energy import and export: No (hint: Default: No). Do you want to exclude device from summary: No (hint: Default: No). Below, three dropdowns: L1 is connected to main feed: L1; L2 is connected to main feed: L2; L3 is connected to main feed: L3. Buttons at the bottom: Back (left), Done (right, dark).
5.4 Test communication
Click Test communication at the bottom of the wizard. It reads the Victron MultiPlus II once and saves nothing. If the test succeeds, click Done: only Done creates the device.
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Screenshot of the bottom button bar of a Reduxi Configurator page. Left: button 'Back'. Right: button 'Test communication' (marked with a cyan box) and dark button 'Done'.
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Screenshot of the Reduxi Configurator page 'Communication channel and device configuration'. Connection *: TCP/IP (dropdown). IP *: 192.168.50.243, with button 'Scan for IP'. Port *: 502, with button 'Test port'. Modbus unit ID *: 1. Buttons at the bottom: Back (left), Test communication and Done (right). The Done button is marked with a cyan box.
6 Check the readings
6.1 Last measurements
After communication is established, check the values of the device 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. Only then do strategy commands affect the device.
Define a strategy as described in Strategies for Reduxi controller.
✓ Summary
Preparation (Points 1–2): Open the Victron manuals. Prepare the MultiPlus-II, the GX device, the controller and the network connection.
Victron system (Point 3): Enable Modbus-TCP on the GX device. Note the unit ID.
Add to Reduxi (Points 4–5): Log in to the Reduxi Configurator. Add the device, select the communication channel and set reading and writing delay to 250. Run Test communication, then click Done.
Go live (Point 6): Check the last measurements. Set the control type to AUTO.
→ Common issues
| Issue | Solution |
|---|---|
| Test communication fails | Check that Modbus-TCP is enabled on the GX device under Settings – Services. Check the unit ID under Settings – Services – Modbus/TCP – Available services. |
| 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. |