Victron PowerAssist is a MultiPlus-II feature that lets you run loads bigger than your shore power or generator can supply. You set a maximum input current. When your loads go over it, the MultiPlus-II tops up the difference with power from the battery. When the loads drop, the spare shore power recharges the battery. It’s why a 30A or even 15A pedestal can run more than it should.
How Victron PowerAssist Works
It builds on a second feature, PowerControl. Victron’s datasheet describes PowerControl like this: you set a maximum grid or generator current, and the MultiPlus-II takes account of other AC loads and uses whatever is left for battery charging, so the source isn’t overloaded.
PowerAssist “takes the principle of PowerControl to a further dimension,” in Victron’s words. Peak power is often needed only for a short time, so the MultiPlus-II makes up for insufficient generator, shore or grid power with battery power. When the load drops, the spare power goes back into the battery.
In practice:
- You set the AC input current limit to match your source (for example, the breaker on the pedestal).
- Below that limit, shore power runs your loads and charges the battery.
- Above it, the charger backs off first, then the inverter adds battery power alongside shore power.
Setting Ranges
The current limit for PowerControl and PowerAssist has a set range. From Victron’s MultiPlus-II 2x120V manual:
| Model | PowerAssist setting range |
|---|---|
| 3000VA | 9.5-50A |
| 4k | 9.5-50A |
| 5000VA | 10.9-100A |
On the 2x120V model, PowerAssist works on the L1 input only. Victron’s 120V datasheet mentions a current sensor option that extends PowerControl and PowerAssist to 100A in grid-parallel setups.
What Limits PowerAssist?
PowerAssist doesn’t create power. Two things cap it:
- The inverter’s rating. The extra power comes from the inverter. For example, the MultiPlus-II 2x120V 12/3000 is rated at 2400W continuous at 25°C, with 5500W peak.
- The battery. Every minute of assist drains it. Long, heavy loads on a small bank will run it down.
So PowerAssist suits short peaks: a microwave, a coffee maker, an air conditioner starting up. It’s not a fix for running large loads all day on a 15A cord.
Setting It Up
PowerAssist is on by default in the MultiPlus-II 2x120V manual’s factory settings. You adjust the input current limit in VictronConnect, VEConfigure or from a GX device. Many people change it every time they move to a new pedestal, so a GX device or Digital Multi Control panel near the door is handy.
See the MultiPlus-II.
Worked Example: A 30A Pedestal and a Busy Kitchen
An RV on a 30A pedestal with the input current limit set to 30A. At 120V, that’s roughly 3,600W from shore power (estimate).
| Load | Watts (est.) |
|---|---|
| Air conditioner running | 1,500W |
| Microwave | 1,200W |
| Electric kettle | 1,500W |
| Total | 4,200W |
Estimates based on common appliance ratings. With all three running, the load is about 600W over what the pedestal provides. PowerAssist supplies that 600W from the battery, well within the 2,400W continuous inverter rating, so the pedestal breaker doesn’t trip. Once the kettle and microwave finish, the spare shore power goes back into the battery.
Worked Example: How Much Battery Does It Use?
Using the same 600W shortfall for 10 minutes:
- Battery energy: 600W × 10 ÷ 60 ≈ 100Wh, plus about 10% for inverter losses, so roughly 110Wh.
- From a 12V battery: about 9Ah.
Estimates. That’s a small share of even a 200Ah bank, and the charger replaces it within minutes once the load drops.
Worked Example: A 15A Household Outlet
At a friend’s driveway on a 15A outlet, set the input limit to about 12A to leave margin. That’s roughly 1,440W from shore power (estimate). An air conditioner at 1,500W running alone needs only a small top-up. Add a microwave and PowerAssist covers about 1,260W from the battery. That suits short periods, but for longer air conditioner use the battery will slowly run down, so check the state of charge.
Choosing the Right Input Current Limit
| Source | Suggested setting (est.) |
|---|---|
| 15A household outlet | 12A |
| 20A outlet | 16A |
| 30A RV pedestal | 25–30A |
| 50A RV pedestal (2x120V) | Up to 50A per leg |
| Small 2,000W inverter generator | About 14–15A |
Setting a little below the source’s rating leaves margin for other loads on the same circuit.
PowerAssist and Generators
On a generator, PowerAssist lets you use a smaller, quieter and more fuel-efficient unit. The MultiPlus-II charges the battery during light loads and adds battery power during peaks, so the generator runs closer to its rating without being overloaded. A Cerbo GX can also start the generator automatically when the battery drops to a set level.
Monitoring PowerAssist in Action
A Cerbo GX or VictronConnect shows shore power, battery power and AC loads at the same time. During a peak, you’ll see the battery flow switch from charging to discharging, then back to charging once the load drops. That’s an easy way to confirm your current limit is set correctly.
PowerAssist vs a Bigger Shore Connection
PowerAssist is ideal for short peaks: cooking, a kettle, a hair dryer or an air conditioner starting up. For long periods of heavy loads, such as running two air conditioners all afternoon, the battery provides energy continuously and will run down. In that case, plan around a larger pedestal, a generator or staggered loads, and let PowerAssist handle the brief overlaps.
FAQ
Does PowerAssist work on a generator?
Yes. Victron’s datasheet says it works with a generator, shore or grid source.
Can PowerAssist run a 240V air conditioner on 120V shore power?
No. On the 2x120V model, 240V loads only run when a split-phase source is connected.
Does PowerAssist need a lithium battery?
No, but the battery has to handle the extra discharge current.
Do I need to change the input limit at every campsite?
Yes, it’s worth setting it to match each pedestal or generator. A Digital Multi Control or GX Touch near the door makes this quick.
Can PowerAssist trip the pedestal breaker?
With the input current limit set at or below the breaker rating, PowerAssist is designed to keep shore current under that limit by adding battery power instead.
Sources: MultiPlus-II 120V and 2x120V datasheets; MultiPlus-II 2x120V manual, section 5 Configuration, victronenergy.com, accessed Oct 2026.
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