Victron Energy MultiPlus-II 48V 5kVA 120V AC Output, 70A Battery Charger, Low Frequency Inverter-Charger, UL 1741

About the Victron MultiPlus-II 48V 5kVA Inverter-Charger

The MultiPlus-II is a low-frequency inverter-charger built around an iron-core transformer, which is what gives it the 9,000W surge capacity from a 4,000W continuous rating. That 2.25:1 surge ratio means welders, compressors, well pumps, and motor-driven appliances start smoothly without tripping breakers or causing voltage sags. The pure sine wave output is equally clean for the other end of the spectrum: sensitive electronics, audio equipment, medical devices, and networking gear all run exactly as they would on utility power.

The built-in 70A battery charger handles bulk charging at scale, and idle consumption sits at just 15W, dropping to 3W in search mode. For a low-frequency inverter at this power level, 15W idle is exceptionally low and makes a measurable difference in overnight standby losses on off-grid systems.

This unit is UL 1741 certified, which means straightforward permitting for battery-based power systems in most US jurisdictions.

One Unit for 120V, Two for 120/240V

A single MultiPlus-II delivers 120V at 4,000W continuous. That covers most essential circuits and works well for dedicated subpanels, outbuildings, or systems where 240V isn't required. When you need full residential 120/240V split-phase (for HVAC, well pumps, electric ranges, dryers), a second unit of the same model pairs over VE.Bus cabling to deliver 8,000W continuous across both legs. This means you can start with one unit today and add the second when your system grows.

For even more capacity, up to six units can parallel on a single phase, and three-phase configurations are supported for commercial applications. Six units on 48V deliver 24,000W continuous with 420A of combined charging capacity.

PowerAssist and PowerControl

PowerControl lets you set a maximum AC input current to match your source. If you're running a generator or feeding from a limited utility circuit (a 30A breaker in a subpanel, for example), the MultiPlus-II limits its total draw to whatever you configure and uses the remaining capacity for battery charging. It accounts for other loads on the circuit too, so the total stays within your set limit.

PowerAssist takes this further. When load demand exceeds what the AC source can deliver, the inverter supplements the difference with battery power, adding up to 4kW on top of the incoming AC. A 30A circuit effectively becomes a 30A-plus-battery source that handles temporary spikes well beyond what the wiring alone could support. When demand drops back down, the excess AC power automatically diverts to battery charging. The system continuously balances input, output, and battery state without manual intervention.

With the optional external 100A current sensor, PowerControl and PowerAssist extend to cover whole-panel monitoring for residential applications.

Dual AC Outputs

The first AC output is battery-backed with automatic transfer. When grid or generator power drops out, the MultiPlus-II switches to inverter mode in under 20 milliseconds. That's fast enough that computers, networking equipment, and refrigerators reliably continue running without resetting. Critical loads belong on this output.

The second AC output is live only when external AC power is present on the input. When the grid or generator goes down, AC Out 2 shuts off. This makes it the right connection point for loads you don't want draining your battery bank: a water heater, clothes dryer, or any high-draw appliance that would burn through stored energy too quickly. These loads still benefit from PowerControl current management while AC is available, but they won't touch your batteries during an outage.

The Victron Ecosystem

The MultiPlus-II isn't just an inverter. It's the core of a system that grows with you. Add a SmartSolar MPPT charge controller for solar. Add a Cerbo GX or Ekrano GX for a touchscreen display and full remote monitoring through Victron's VRM portal, which is free with every system, forever, with zero subscription fees. Add a Lynx Distributor for fused DC distribution with integrated monitoring. Every component communicates over a shared data backbone, and the entire system is visible and configurable from anywhere with an internet connection.

Firmware updates are free and ongoing. Victron actively develops new features and pushes them to existing hardware. The MultiPlus-II you install today gets better over time rather than going stale.

Initial setup requires a computer with the MK3-USB interface and VE.Configure software. This is where you set charge parameters, PowerAssist thresholds, AC input limits, relay behavior, and assistant programming. Once configured, the VictronConnect app and VRM portal handle day-to-day monitoring and remote adjustments.

For a ready-to-build solution, check out the Residential 10kVA 120/240V Off-Grid Power System Kit featuring two MultiPlus-II units in split-phase configuration with a complete Lynx distribution system.