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Victron Galvanic Isolator VDI-16 – Marine galvanic isolator

(1 customer review)

£109.87 £106.00 Save 4%

Galvanic isolators protect your vessel from galvanic corrosion, and provide one-off protection from short circuits, power surges, and lightning strikes when connected to shore power.

  • Max current 16A
  • Prevents excessive wasting of your sacrificial anodes when connected to shore power
  • Fail-safe – in the event of a short circuit, power surge, or lightning strike, the diode in the isolator fails in the ‘safe’ position, protecting your vessel’s electrical systems

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SKU: GDI000016000 Category:

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    Victron Galvanic Isolator VDI-16 – Marine galvanic isolator for corrosion protection

    The Victron galvanic isolator VDI-16 provides protection from galvanic corrosion, and from short circuits and power surges in your vessel.

    Why do you need a galvanic isolator?

    Galvanic corrosion happens to all metal components on a boat that are exposed to seawater. Normally, your sacrificial anodes are enough protect your shaft and propeller from galvanic corrosion. However, when you connect to an onshore electrical hookup, safety demands that you also be connected to an onshore ground. This essentially creates a low voltage battery, incorporating your boat, the water, and the ground. Without any sort of protection, the current flow through this battery will significantly speed up the galvanic corrosion process.

    You can protect against this battery effect by installing either a galvanic isolator or an isolation transformer.

    Galvanic isolators and isolation transformers

    Both galvanic isolators and isolation transformers achieve the same thing. They isolate your boat from the low voltage battery effect, protecting underwater metals from corrosion and preventing your sacrificial anodes from wasting too quickly. The difference is in how they achieve this.

    A galvanic isolator is a small, lightweight device that prevents low voltage currents from passing between your boat and the shore. Because the battery effect current is generally less than 1V, it can’t pass, and your boat is protected. At the same time, high voltage currents, such as those that happen during a short circuit or power surge, can safely pass through to the ground.

    An isolation transformer achieves protection by creating a physical separation between your boat and the onshore hookup. They replace the wired connection with an electromagnetic connection – power passes through the air by an electromagnetic field. This physical gap prevents the low voltage battery effect from occurring.

    Galvanic isolators and isolation transformers – pros and cons

    A galvanic isolator is significantly cheaper and simpler than an isolation transformer. This simplicity results in a tradeoff in reliability. Galvanic isolators are prone to damage by surges and lightning, meaning that you need to periodically check your isolator to make sure it’s still working. An isolation transformer is very resilient to power surges and lightning strikes – it’s an ‘install and forget’ device.

    Additionally, galvanic isolators can only protect against currents lower than 1.4V. When connected to a shore hookup that’s working properly, this isn’t a problem. However, a shore hookup that’s slightly faulty can result in a ground connection which carries a voltage. This small voltage won’t cause a detectable problem in itself, but it can be enough to bypass the galvanic isolator, eliminating the corrosion protection that it provides. An isolation transformer doesn’t have this weakness.

    Isolation transformers also perform other functions besides protection from galvanic corrosion. An isolation transformer is able to accommodate a wide range of input voltages, making them popular with people who travel the world in their boats and connect to onshore hookups with differing voltages.

    Besides the higher cost, the other main drawback of an isolation transformer is its significant size and weight.

    Which one is right for me?

    In short, a galvanic isolator is a relatively cheap and simple device that will protect your boat from galvanic corrosion under most circumstances. However, it does nothing else and can fail or be bypassed, requiring it to be regularly checked, and replaced if necessary.

    A galvanic isolator will not fail and won’t need replacing, and in addition it allows you to connect to almost any onshore hookup in the world.

    Cost, resilience, and flexibility should determine whether you choose either a galvanic isolator or an isolation transformer for your boat.

    We also sell isolation transformers in our shop; check them out here.

    Looking for a differently sized galvanic isolator?

    Take a look at our other options here.

    Products that give back

    We are members of 1% for the Planet. This means that for every product purchased from Nohma, we will give 1% of the total cost to The Honnold Foundation, to provide solar power to underprivileged communities. If you want your electrical system to have more of a positive impact, purchasing your components from us at Nohma will mean you can give back as well as powering your off-grid system.

    Product SKU: GDI000016000

    Weight 1 kg
    Dimensions 6 × 12 × 20 cm

    Victron Energy

    Peak current (20ms)


    Protection category



    5 years

    Product or kit


    1 Review 5.00

    1. BILLY S.

      As always a pleasure dealing with the Climbingvan team. I’ve dealt with 4 members of the team on different occasions and they’re all as delightful as one another.

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