To program a Victron MultiPlus-II, you need a way to talk to its VE.Bus port and some free Victron software. Victron’s manual lists the hardware as an MK3-USB (VE.Bus to USB) interface and an RJ45 UTP cable. From there you can use the VictronConnect app or VEConfigure on a computer. Here’s what each tool does and what to set before you switch on.
Electrical work can be dangerous: follow the manual, fuse and size every cable correctly, and use a licensed electrician for anything connected to household wiring.
Tools to Program a Victron MultiPlus-II
| Tool | What it’s for |
|---|---|
| MK3-USB + RJ45 UTP cable | Connects a computer or phone to the VE.Bus port |
| VictronConnect app | General configuration of a single MultiPlus |
| VEConfigure | Full settings on a PC |
| VE.Bus Quick Configure Setup | Up to three units in parallel or three-phase |
| VE.Bus System Configurator | Advanced systems with four or more Multis |
All of this software is free from victronenergy.com. The datasheet also lists Bluetooth monitoring and control with the optional VE.Bus Smart dongle, and remote access through a GX device and VRM.
Before You Start
Victron’s manual is clear on two points:
- Settings may only be changed by a qualified electrical engineer.
- Remove AC input during configuration.
Many people bench-program the unit on a battery before installing it, which matches that advice.
Factory Defaults Worth Checking
The MultiPlus-II 2x120V ships with these defaults, per its manual:
- Battery type: Victron Gel Deep Discharge (also suitable for Victron AGM Deep Discharge)
- Absorption 14.4V / 28.8V, float 13.8V / 27.6V, storage 13.2V / 26.4V
- Charging current at 100% of the maximum
- Inverter output 120VAC, 60Hz
- PowerAssist on, UPS feature on, ground relay on
Victron warns that the standard charging voltage may not suit your batteries. If you have lithium, check your battery maker’s numbers.
Settings Most People Change
- Battery charge settings to match your battery type.
- Charge current, so you don’t overload a small generator or shore connection.
- AC input current limit, which sets where PowerControl and PowerAssist kick in.
- UPS feature, which Victron says to turn off if the unit fails to sync with an unstable generator.
- Input voltage range lower limit. Victron suggests raising it to 110VAC for synchronous AVR generators that cause shutdowns.
- Parallel or three-phase setup, using Quick Configure or System Configurator.
Remote Changes
With a Cerbo GX or other GX product online, Victron says settings can be changed remotely through VRM.
See the MultiPlus-II and the MK3-USB interface.
Worked Example: Setting Up a MultiPlus-II 12/3000 for a 200Ah Lithium Bank
A common RV or van configuration, done on the bench with AC input disconnected:
- Connect: plug the MK3-USB into the VE.Bus port with an RJ45 UTP cable and open VictronConnect (or VEConfigure on a PC).
- Battery type: switch from the Gel default to a lithium profile, or enter your battery maker’s values, for example 14.2V absorption and 13.5V float.
- Charge current: the 12/3000 can charge at up to 120A. For a 200Ah LiFePO4 battery rated for 100A charging, set 100A or less.
- AC input current limit: 30A for a 30A RV pedestal, or lower for a small generator.
- Low battery shutdown: set to suit the battery’s BMS, so the inverter stops before the BMS has to disconnect.
- Save and test: reconnect AC, confirm it passes through and charges, then remove AC and check it inverts.
Example values; always follow your battery’s datasheet.
Worked Example: Setting the Charge Current for a Generator
A 2,200W inverter generator can deliver roughly 18A at 120V continuously (estimate: 2,200W ÷ 120V × 0.95 headroom). With the AC input current limit set to 16A, PowerControl reduces charging automatically when loads on the output rise, so the generator isn’t overloaded. Then, with the charge current at, say, 80A on a 12V battery, the charger draws about 80 × 14.4 ÷ 0.9 ≈ 1,280W from the generator (estimate), which leaves room for loads.
VictronConnect vs VEConfigure: Which to Use
| Task | VictronConnect | VEConfigure |
|---|---|---|
| Battery charge settings | Yes | Yes |
| Input current limit, PowerAssist, UPS | Yes | Yes |
| Phone or tablet use | Yes (with MK3-USB or VE.Bus Smart dongle) | No, PC only |
| Assistants (such as ESS or generator start) | Via VE.Bus System Configurator / VEConfigure | Yes |
| Saving a settings file | Yes | Yes |
For a single unit with standard settings, VictronConnect covers most needs. VEConfigure gives access to every setting and to Assistants.
Assistants
Assistants are add-on programs loaded into the MultiPlus through VEConfigure. Common ones include ESS for grid-tied self-consumption, a two-signal BMS assistant for some lithium setups, and programmable relay logic for generator start. A GX device can also handle generator start without an Assistant, through its own relay.
Saving a Backup of Your Settings
Once the unit works the way you want, save its configuration file from VictronConnect or VEConfigure. If you ever replace the unit or reset it, loading the file restores every setting in one step. Keep a copy with your system’s wiring diagram.
Firmware Updates
VictronConnect checks VE.Bus firmware when it connects through an MK3-USB and can update it. On larger systems with several units, Victron’s update instructions and a GX device with remote VEConfigure can make it easier to keep every unit on the same firmware.
Settings for a Parallel or Split-Phase Pair
Two MultiPlus-II units can share a load in parallel for more power, or run as a split-phase pair for 120/240V output. Victron’s VE.Bus Quick Configure Setup handles up to three units. The basic steps:
- Connect the units to each other with RJ45 UTP cables on the VE.Bus ports, with all AC input disconnected.
- Make sure every unit has the same firmware and the same model.
- Run Quick Configure and choose parallel or split-phase.
- Apply your battery and charge settings, which are shared across the system.
Matching cable lengths on the DC side of each unit helps the units share current evenly, as Victron’s manual describes.
A Settings Checklist to Keep
Write down, or save in the configuration file: battery type and voltages, charge current, AC input current limit, PowerAssist on or off, UPS feature on or off, input voltage range and any Assistants. Having that list makes future changes and troubleshooting much quicker.
FAQ
Do I need an MK3-USB?
Victron’s manual lists it as the required hardware for configuring.
Can I program several Multis at once?
Use VE.Bus Quick Configure for up to three, and VE.Bus System Configurator for four or more.
Should the AC input be connected while programming?
No. Victron says to remove it.
Can I program a MultiPlus-II over Bluetooth?
Yes, with the optional VE.Bus Smart dongle connected to the VE.Bus port, VictronConnect can configure and monitor the unit.
Will programming erase my settings?
No. Changing a setting only changes that value. Saving a configuration file first gives you a backup either way.
Sources: MultiPlus-II 2x120V manual, section 5 Configuration; MultiPlus-II 2x120V datasheet, victronenergy.com, accessed Oct 2026.
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