120A OR 220A CHARGER
Serious charge current back into a 12V bank from shore power or a generator, not a trickle.
SWITCHES OVER IN UNDER 20ms
Fast enough that computers and sensitive gear ride through a mains failure. It is a UPS as well.
2400W OR 4000W CONTINUOUS
With 5500W and 9000W peaks for motors and compressors starting up.
POWERASSIST BOOSTS A SMALL SUPPLY
Covers the shortfall from the battery when a generator or shore supply cannot meet a peak.
5 YEAR VICTRON WARRANTY
Backed by a 5 year limited warranty, with free remote monitoring through the VRM portal.
The MultiPlus-II is a combined pure sine inverter and battery charger with two AC outputs, built for professional marine, vehicle and off-grid work as well as grid-connected energy storage. The 12V models are the ones we fit most often in workshop builds, where a vehicle or van needs proper 230V power rather than a small standalone inverter.
The 3kVA is the 12/3000/120-32. It delivers 3000VA, which is 2400W continuous at 25°C, carries a 5500W peak for motor startup and other short surges, and charges at up to 120A. The 5kVA is the 12/5000/220-50, delivering 5000VA or 4000W continuous with a 9000W peak and a 220A charger, which is a serious amount of current back into a 12V bank from shore power or a generator.
Worth knowing before you size a system: continuous output derates with heat. The 3kVA drops to 2200W at 40°C and 1700W at 65°C, and the 5kVA to 3700W and 3000W. In a hot engine bay or an enclosed cabinet, design around the 40°C figure rather than the headline one.
Two features do most of the work in practice. PowerAssist lets the unit fill the gap when a generator or shore supply cannot meet a peak, drawing the shortfall from the battery and then recharging it once the load drops, which means a small supply can run bigger loads than it otherwise could. PowerControl works the other way, capping the current drawn from that supply so you never trip the source.
The transfer switch changes over in under 20 milliseconds, fast enough that computers and sensitive electronics do not notice the change, so it doubles as a UPS. There are two AC outputs: the main one is uninterrupted, while the second is live only when AC input is present. That second output is where a water heater or anything else that must not flatten the battery should go.
Systems can be scaled by paralleling up to six units, or configured for three phase. Setup is done through VEConfigure, and adding a Cerbo GX or similar brings remote monitoring and configuration through the free VRM portal. It works with lead acid and lithium alike, with an adaptive charge algorithm that adjusts to suit.
Quick Specs
User Manuals
Warranty
covering manufacturing defects and faults under normal use.