Wireless Charging

Wärtsilä has developed a wireless charging system for easy transfer of power from the shore to ship, replacing the traditional cable connection method. This technology is particularly suitable for fully electric vessels using batteries which spend little time at the dock, such as ferries for example. Using the Wireless Charger, power transfer can start the moment the vessel is docked rather than having to wait until cables are connected. This means that the same energy can be supplied to the vessel over a longer time, which reduces the total power rating of the shore connection system.

When combined with systems such as auto-docking and vacuum mooring then the process of docking and undocking becomes even more safe and efficient.

    Charger Concepts

    The wireless charger has a sending coil arrangement on-shore mounted on a hydraulic arm with y and z axis movement. The sending coil is connected to a nearby power electronic where grid connection and alternatively shore based energy storage can be connected. The input voltage to the power electronics is 690V 50/60Hz.

    On the ship side there is a similar coil arrangement where the receiving coil plate is mounted flush with the side of the vessel. The coil arrangement is connected to a rectifier for DC conversion.

    The basic principle is following:

    • Current in inductive sending coil creates a controlled magnetic field.
    • Magnetic field from sending coil creates a current in the receiving coil.
    • High frequency current flowing in the inductive coil is converted to DC Power.
    • Energy is stored in the ship batteries

    This system can transfer more than 2 MW with a distance between the coils of about 4- 500 mm.

    Capacity of the Wärtsilä wireless charger
    One standard basic unit delivers 2.5MW. Landside and onboard connections are normally 690VAC, but that can be adapted with transformers and there is also the possibility for a common DC bus connection. At 690V, 2.5MW corresponds to 2500Arms three phase. The power rating of the charging system can easily be increased by using several units in parallel, or by specifying a larger unit with an increased active coil area.

    Key Benefits

    The Wärtsilä Wireless Charging System has the following benefits:

    Lifecycle cost

    • Low wear
    • Low maintenance
    • Low lifecycle cost

    Safety and availability

    • High safety
    • High availability
    • Excellent weather protection
    • No cable connections ship to shore
    • Encapsulated insulation, no creepage distances exposed to weather
    • No galvanic connection ship to shore
    • No consequences of relative movement ship vs shore
    • Immune to ice and snow
    • Prepared for de-icing


    • Prepared for autonomous operations

    Grid cost / landside battery cost

    • Low power/energy ratio –may avoid weak grids upgrading – may avoid shoreside battery
    • Active rectifiers stabilize grids
    • High charging time/docking time ratio


    • Low profile landside
    Wireless charging is best suited for applications where a high number of charging periods per day are necessary. This is especially true in harsh marine climates, since wireless charging systems experience no contact wear and have no exposed electrical contacts. Ferries definitely fall within this category, as do tugs and other coastal vessels, depending upon their actual operational profile. More advanced applications may also benefit from the advantages of having a total separation between the primary and secondary systems. With the introduction of more automated, and even autonomous vessels, inductive charging is designed and tested to offer a completely automated procedure where no human interaction is necessary.

    Frequently asked questions

    • How much jetty infrastructure work is needed, and is a high energy power supply needed from the grid to the jetty?
    • What are the charging and heat losses, the cycles available, and the battery life?
    • What are the losses and system efficiency of the wireless charging system?
    • What are the options for locations onboard the vessel and on the jetty?
    • What is the expected operational life of the equipment, and the average annual maintenance costs for it?
    • Does proximity to eg. navigation, automation, electromagnetic systems or electromotive fields, medical devices, mobile phones etc. cause any kind of interference/danger to the devices or personnel?
    • Is the wireless charging system affected by extreme weather conditions or eg. possible ice build-up?

    download wireless charging

    More answers to common questions about wireless charging

    Didn’t you find the answer you were looking for in the above FAQ section? Download this full document where we have gathered even more frequently asked questions and answers regarding Wärtsilä’s wireless charging system for easy transfer of power from shore to ship.

    Press releases


    The evolution of wireless charging

    Power cords may soon be a thing of the past. Everything from mobile phones to coastal ferries can be...
    21 June 2017
    • Twentyfour7. article

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