All guides · Shore power and installation
I wanted to create a single budget for everything that uses shore power. The electric kettle, water heater, and battery charger all share the available power, even when they are plugged into different outlets on board.
How many watts are available?
At 230 V, you can use voltage multiplied by current as a first estimate. The table shows loads with a power factor of 1; motors and electronic equipment may require an assessment of both watts and VA. The remaining limitations of the installation still apply.
| Connection | Theoretical power at 230 V |
|---|---|
| 6 A | 1,380 W |
| 10 A | 2,300 W |
| 16 A | 3,680 W |
The harbor outlet does not permit loading the boat's cable or installation beyond their limits. Also, check the harbor's terms and the specific supply. A plug with a certain rated current does not alone indicate which fuse is installed upstream.
Example: coffee and hot water at 6 A
A 1,000 W electric kettle and a 750 W heater use a total of 1,750 W. This is more than the 1,380 W in the table, even before the battery charger is included. A practical solution might be to heat water in turns and reduce charging if the charger supports it.
A 30 A charger does not draw 30 A from the harbor
The charger's stated amperage is usually the current on the battery side. As a rough estimate, 14 V × 30 A gives a charging power of 420 W. The charger must draw more than this from the shore power due to losses; use its input data for the final budget.
Power limitation and battery assist
On relevant Victron MultiPlus systems, PowerControl can reduce charging to make room for other loads within the set input limit. PowerAssist can supplement from the battery during higher loads. This requires a correctly dimensioned and configured solution.
Battery assist uses stored energy. It cannot turn a small harbor supply into an unlimited energy source. I would write both normal consumption and short peak loads on a note by the electrical panel, so everyone on board knows which appliances can be used simultaneously.
Sources and manufacturer documentation
Manufacturer documentation checked September 2026. Always follow the manual for the specific model and installation. The calculation examples are simplified examples for planning purposes.
Proceed with your solution
Let me know what shore power you normally have and which appliances you want to use at the same time, and I will help you with the power budget.