Victron Energy
Victron MultiPlus-II 12/3000/120-50 120V Inverter/Charger
Victron MultiPlus-II 12/3000/120-50 120V Inverter/Charger
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Victron MultiPlus-II 12/3000/120-50 120V Inverter/Charger
The Victron MultiPlus-II 12/3000/120-50 120V combines a pure sine wave inverter, powerful 120A battery charger and 50A automatic transfer switch in one integrated unit. Designed for 12V battery systems, it is an excellent choice for RVs, boats, service vehicles, off-grid cabins and backup-power installations.
When shore power, utility power or a generator is available, the MultiPlus-II passes that power through to connected loads while charging the battery. If the AC source is disconnected or rejected, it changes to inverter power in less than 20 milliseconds—fast enough that most computers and electronic equipment continue operating without interruption.
| Rating | What It Means |
|---|---|
| 12 | Designed for a nominal 12V battery bank |
| 3000 | 3000VA inverter rating with 2400W continuous real-power output at 25°C |
| 120 | Up to 120A of battery charging from an available AC source |
| 50 | 50A AC input and automatic transfer-switch capacity |
PMP122305122 has one 120V AC input and supplies 120V AC output. It is not the MultiPlus-II 2×120V model and does not independently supply 120/240V split-phase power from a single unit.
Why You'll Love It
- 3000VA pure sine wave inverter with 2400W continuous output at 25°C
- Up to 5500W of short-duration peak power for compatible starting loads
- Powerful 120A adaptive battery charger for 12V battery banks
- Built-in 50A automatic transfer switch with less than 20ms transfer time
- PowerControl and PowerAssist for limited shore-power and generator sources
- Two AC outputs for separating inverter-backed and source-dependent loads
- Expandable VE.Bus platform with optional Bluetooth, GX monitoring and remote controls
Strong Starting Power for Demanding Loads
With up to 5500W of peak power, the MultiPlus-II has the short-term output needed to start many compatible refrigerators, pumps, compressors and other motor-driven appliances.
Its continuous inverter rating is 3000VA, with up to 2400W of continuous real-power output at 25°C. This combination provides dependable everyday power along with substantial extra capacity for brief startup surges.
Available starting power depends on the appliance, battery condition, BMS discharge rating, DC cable size and voltage drop. A properly designed battery system helps the MultiPlus-II deliver its full starting capability.
Automatic Transfer Between AC and Battery Power
When an acceptable 120V AC source is connected, the MultiPlus-II transfers that power to AC-out-1 and uses available capacity to charge the battery. If the source fails, is disconnected or falls outside the configured voltage and frequency limits, the inverter automatically takes over.
Transfer to inverter operation takes less than 20 milliseconds. This makes the MultiPlus-II suitable for applications where refrigerators, communications equipment, computers and other essential loads should continue operating when shore power or generator power is interrupted.
The front switch can be placed in charger-only mode when battery charging and AC passthrough are required but automatic inverter operation is not. If the external AC source disappears, the inverter remains off instead of continuing to power loads from the battery.
PowerControl & PowerAssist
PowerControl allows the maximum AC input current to be adjusted for the connected source. The MultiPlus-II accounts for the power being used by AC loads and reduces battery charging when necessary to avoid overloading a limited shore-power connection or generator.
PowerAssist goes one step further. When a temporary load exceeds the available shore or generator capacity, the MultiPlus-II can add inverter power from the battery. Once the load decreases, available AC power can again be used to recharge the battery.
The 50A rating is the maximum AC input capacity—not the minimum required source size. The input-current limit can be reduced for a compatible 15A, 20A or 30A connection. The setting must match the available source and installed AC protection.
Two AC Outputs for Better Load Control
AC-out-1 is the primary output. It remains powered from the inverter when shore, generator or utility power is unavailable.
AC-out-2 is a source-dependent auxiliary output rated for up to 32A. It disconnects when the MultiPlus-II changes to battery operation and reconnects after acceptable AC input returns.
This second output is useful for equipment that should operate only when shore power or a generator is available, such as an electric water heater or another non-essential load that should not discharge the house battery.
AC-out-2 is not powered during battery-only operation. It is specifically intended for loads that should be automatically disabled when the system is running from the battery.
120A Adaptive Battery Charging
The built-in charger can supply up to 120A to a compatible 12V battery bank. Charging current and voltage settings can be adjusted to meet the requirements of LiFePO₄, AGM, gel and flooded lead-acid batteries.
The four-stage adaptive charging system uses bulk, absorption, float and storage stages. For lead-acid batteries, the adaptive algorithm adjusts absorption time based on the preceding discharge and reduces long-term float voltage when the battery remains unused.
- Maximum 120A battery-charging current
- Adjustable charging current and voltage settings
- BatterySafe and storage modes for lead-acid batteries
- Battery voltage-sense connection for cable-drop compensation
- Battery temperature sensing
- Two programmable input/output ports for compatible BMS integration
- Maintenance-charging output for a separate 12V starter battery
The factory charging profile may not be correct for every battery. Charging voltages, maximum current, low-voltage shutdown settings and any required BMS communication must be configured for the installed battery system before regular operation.
Battery Bank Requirements
At full continuous inverter output, a 12V battery system may need to supply more than 200A after allowing for battery voltage and inverter losses. Starting surges can require considerably more current for a short period.
The battery bank, internal BMS, busbars, disconnects, fuse and cabling must all be capable of supporting the inverter's continuous and surge current. Victron lists a recommended battery-bank range of approximately 400Ah to 1200Ah for this model.
The 24V MultiPlus-II provides the same 3000VA inverter rating and 2400W continuous output while drawing roughly half as much DC current for an equivalent AC load. A 24V system may simplify battery, BMS, busbar and cable planning in higher-power installations.
Monitoring, Bluetooth & System Control
The MultiPlus-II uses VE.Bus for communication and system integration. It does not include built-in Bluetooth or a VE.Direct port.
| Monitoring Option | What It Provides |
|---|---|
| VE.Bus Smart Dongle | Optional local Bluetooth monitoring, on/off or charger-only control and AC input-current adjustment through VictronConnect |
| MK3-USB Interface | Direct computer connection for detailed VE.Bus configuration and firmware work |
| Digital Multi Control | Panel-mounted on/off or charger-only control with an adjustable AC input-current limit |
| Cerbo GX | Central system monitoring, Remote Console, optional VRM internet access and integration with other Victron equipment |
The MultiPlus-II does not connect directly to VictronConnect by Bluetooth. An optional VE.Bus Smart Dongle can add convenient local monitoring and basic control, but it does not replace an MK3-USB interface or compatible GX device for every advanced configuration task.
Compatible Generator Integration
The MultiPlus-II can accept compatible 120V generator power through its AC input. PowerControl can reduce battery charging to stay within the generator's available output, while PowerAssist can supplement short periods of higher demand from the battery.
The programmable dry-contact relay can also be configured for generator start and stop control. This is generally suitable for a generator or generator controller that accepts a compatible two-wire start signal.
The relay can be programmed to respond to conditions such as battery voltage or load. The correct generator interface, control logic and configuration are installation-specific. A Cerbo GX can provide more extensive generator start/stop conditions and monitoring when required.
DC Cabling, Fuse & Installation Planning
A 3000VA inverter operating from a 12V battery bank requires extremely low-resistance DC connections. Cable length, conductor size, terminal quality, fuse selection and connection torque directly affect starting performance, charging accuracy and system reliability.
| Victron Installation Reference | Published Guidance |
|---|---|
| Suggested Battery Capacity | 400Ah to 1200Ah |
| DC Fuse | 400A |
| DC Cable Length up to 5m | Two AWG 1/0 positive and two AWG 1/0 negative conductors |
| DC Cable Length from 5m to 10m | Two AWG 2/0 positive and two AWG 2/0 negative conductors |
| Battery Connections | Two M8 connection points per polarity |
| Battery Terminal Torque | 12Nm |
The values above reproduce Victron's general installation table. Final conductor size, fuse type, disconnects, routing and protection must comply with the complete installation, applicable electrical requirements and the ampacity of the selected cable. Victron specifically states that the battery cables should not be installed in a closed conduit.
The MultiPlus-II contains hazardous AC and high-current DC connections. AC input, output, grounding, neutral switching, branch protection and disconnecting equipment must be designed and installed in accordance with the Victron manual and applicable electrical requirements.
What Else Is Required?
The MultiPlus-II is the inverter, AC charger and transfer switch. It is not a complete electrical system by itself.
- Compatible 12V battery bank with sufficient discharge capacity
- Properly sized battery cables, terminals and busbars
- Battery-side fuse and suitably rated disconnect
- Appropriate positive and negative DC distribution
- AC input and output wiring with required protection
- Separate solar charge controller if solar charging will be used
- Optional monitoring or configuration hardware
Battery cables, fuse protection, AC wiring, solar equipment, VE.Bus cables and monitoring accessories are sold separately unless specifically stated otherwise.
Applications
- RVs, campers and motorhomes
- Boats and marine house-power systems
- Service trucks and mobile work trailers
- Off-grid cabins and small buildings
- Backup power for essential 120V loads
- Generator-supported battery systems
- 12V lithium or lead-acid battery banks
- Systems requiring automatic AC transfer
- Victron systems using Cerbo GX and VRM monitoring
Product Specifications
| Specification | Value |
|---|---|
| Model | MultiPlus-II 12/3000/120-50 120V |
| Victron Part Number | PMP122305122 |
| Nominal Battery Voltage | 12V |
| DC Input Voltage Range | 9.5V to 17V |
| AC Output Voltage | 120VAC ±2% |
| Output Frequency | 60Hz ±0.1% |
| Inverter Waveform | Pure sine wave |
| Inverter Rating | 3000VA |
| Continuous Output at 25°C | 2400W |
| Continuous Output at 40°C | 2200W |
| Continuous Output at 65°C | 1700W |
| Peak Power | 5500W |
| Maximum Efficiency | 93% |
| Zero-Load Consumption | 13W |
| Zero-Load Consumption — AES Mode | 9W |
| Zero-Load Consumption — Search Mode | 3W |
| AC Input | Single-phase 120VAC |
| Accepted AC Input Voltage | 90V to 140VAC, configurable within supported limits |
| Accepted AC Input Frequency | 55Hz to 65Hz |
| Maximum AC Input Current | 50A |
| Transfer Switch | 50A |
| Transfer Time | Less than 20ms |
| PowerControl | Yes |
| PowerAssist | Yes |
| Maximum Battery Charging Current | 120A |
| Default Absorption Voltage | 14.4V |
| Default Float Voltage | 13.8V |
| Default Storage Voltage | 13.2V |
| Charging Algorithm | Four-stage adaptive with BatterySafe mode |
| Starter-Battery Charge Output | Maintenance-charging output for a separate 12V starter battery |
| Primary AC Output | AC-out-1; inverter-backed |
| Auxiliary AC Output | AC-out-2; 32A maximum, available only with external AC input |
| Communication | VE.Bus through two RJ45 ports |
| Built-In Bluetooth | No; optional VE.Bus Smart Dongle required |
| Remote On/Off | Yes |
| Programmable Relay | Yes; alarm, low-voltage or compatible generator start/stop functions |
| Programmable Inputs/Outputs | Two analogue/digital ports |
| Parallel Operation | Up to six identical units with appropriate system configuration |
| Battery Connections | Two M8 connection points per polarity |
| AC Connections | Screw terminals accepting up to 13mm² / AWG 6 |
| Protection Rating | IP22 |
| Cooling | Fan-assisted |
| Operating Temperature | -40°C to +60°C; output derates at elevated temperature |
| Dimensions (L × W × H) | 578 × 277 × 148mm / 22.8 × 10.9 × 5.8in |
| Weight | 19kg / 42lb |
| Listing | UL 458 |
| Safety Standards | CSA C22.2 No. 107.1-16; EN/IEC 60335-1 and EN/IEC 60335-2-29 |
| Warranty | 5 Year |
Specifications are believed to be accurate at the time of publication but may change without notice. While we make every effort to keep product information current, Sapphire Energy cannot guarantee all specifications are complete, error-free or up to date. Please refer to the manufacturer’s documentation if a particular specification is critical to your application. Contact us for help!
Frequently Asked Questions
How much power can the MultiPlus-II provide?
The MultiPlus-II can deliver up to 5500W of peak power to help start compatible refrigerators, pumps, compressors and other loads with a brief startup surge.
| Operating Condition | Output Rating |
|---|---|
| Peak Output | 5500W |
| Continuous Inverter Rating | 3000VA |
| Continuous Real-Power Output at 25°C | 2400W |
| Continuous Real-Power Output at 40°C | 2200W |
| Continuous Real-Power Output at 65°C | 1700W |
Can it supply 240V appliances?
Not by itself. This model has a single 120V AC input and produces 120V AC output.
Split-phase or multi-phase systems can be created with additional compatible Victron equipment and specialized configuration.
Should I choose the 12V or 24V version?
Choose the version that matches the nominal voltage of your battery bank. The two versions provide the same 3000VA inverter rating and 2400W continuous output, but the 12V version has a 120A charger while the 24V version has a 70A charger.
For the same AC load, the 24V version draws roughly half the DC current. This can reduce the demands placed on the battery BMS, busbars and DC cabling.
Can I connect it to a 30A shore-power supply?
Yes. The 50A rating is the maximum accepted AC input current. The input-current limit can be reduced to match a compatible 30A or smaller AC source.
Once correctly configured, PowerControl reduces charging when necessary to keep the combined charger and AC loads within the selected input limit.
What happens when shore or generator power fails?
AC-out-1 changes to inverter power in less than 20 milliseconds. Most computers and ordinary electronics can continue operating without a noticeable interruption.
AC-out-2 switches off because that output is intentionally powered only while an acceptable external AC source is available.
Can it charge lithium batteries?
Yes. It can charge compatible 12V LiFePO₄ batteries when the charging voltages, maximum current, low-voltage settings and any required BMS controls are correctly configured.
The battery and BMS must also support the inverter's continuous and surge discharge requirements.
Does it include a solar charge controller?
No. The built-in 120A charger operates from an AC source such as shore power, utility power or a generator.
Solar panels require a separate appropriately sized solar charge controller connected to the 12V battery system.
Does it have built-in Bluetooth?
No. The MultiPlus-II communicates through VE.Bus and does not have built-in Bluetooth.
The optional VE.Bus Smart Dongle adds Bluetooth monitoring and basic control through VictronConnect. An MK3-USB interface or compatible GX device is required for certain advanced configuration tasks.
Can it automatically start a generator?
Yes, when used with a compatible generator or generator controller that accepts an appropriate two-wire start signal. The MultiPlus-II has a programmable dry-contact relay that can be configured for generator start and stop control.
The relay logic and generator interface must be configured for the specific installation. A Cerbo GX can provide additional generator-control conditions, monitoring and scheduling options.
What size battery bank should I use?
Victron's general recommendation for this model is approximately 400Ah to 1200Ah at 12V. The correct capacity depends on the required runtime, expected loads, battery chemistry, charging sources and permitted depth of discharge.
Capacity alone is not enough—the battery BMS must also support the inverter's continuous and peak current requirements.
What battery fuse and cable does Victron specify?
Victron's installation table lists a 400A DC fuse and two AWG 1/0 positive and two AWG 1/0 negative conductors for cable lengths up to 5m. For lengths between 5m and 10m, it lists two AWG 2/0 conductors for each polarity.
These are manufacturer reference values, not a substitute for installation-specific electrical design. Final cable and fuse selection must account for conductor ampacity, routing, temperature, cable type, local requirements and all connected equipment.
Can multiple units be connected together?
Yes. Up to six identical units can be configured in parallel for additional capacity. Compatible units can also be used in professionally designed split-phase or three-phase VE.Bus systems.
Multi-unit systems require identical equipment, matching DC cabling, VE.Bus communication cables and specialized configuration.
Can it be connected to utility power?
Yes—for incoming power and battery backup, but not as a grid-tied solar inverter. The MultiPlus-II can receive 120V utility power through its AC input, pass that power through to connected loads and use it to charge the battery. If utility power fails, it can automatically switch AC-out-1 to battery-powered inverter operation.
PMP122305122 is UL 458 listed for mobile, marine, off-grid and backup-power applications. It is not UL 1741 listed for utility grid interconnection and should not be used to export battery or solar power into the utility grid as a standalone grid-tie inverter.
Any system intended to operate in parallel with—or export power to—a utility grid must use the required certified equipment and comply with local electrical codes, utility requirements and applicable approvals.
Can you special-order other Victron products?
Yes. We may be able to special-order Victron products that are not currently listed on our website, including alternate MultiPlus configurations, monitoring equipment and system accessories.
Contact us with the Victron model or part number you need and we will confirm availability, pricing and estimated lead time.
What warranty does this product include?
This inverter/charger is backed by Victron Energy's 5-year limited warranty.
If you need troubleshooting or warranty assistance, Sapphire Energy will work with you throughout the process.
Contact us with your battery specifications, largest AC loads, shore or generator capacity, solar array and required runtime. We can help confirm inverter sizing, battery compatibility, charging capacity, monitoring equipment and the additional wiring and protection required for the installation.
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