Galvanic Isolator

[Besonders]

Advice please,
I was thinking of purchasing a Galvanic Isolator as per the ebay link below. My questions are does this device actually prevent or reduce the causes of galvanic Corrosion when connected to shorepower or is it just an indicater of current leakage. There is a lot of sales blurb in the listing but i feel it does not actually address the questions that I Pose. Do I need or would you recommend use of one of these devices. I do have shore power and a Tecpro Tecsup battery charging system

http://www.ebay.co.uk/itm/70-amp-galvanic-isolator-2-yr-warranty-69-99Beat-that-/181100618421?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item2a2a7022b5

Many Thanks

 

[Otter]

Is the mains earth grounded to your battery negative? If not then a GI will do nothing.

 

[VicS]

If you leave the shore-power connected ... that's connected, not necessarily in use, ... then a galvanic isolator is next to essential to prevent excessive rate of corrosion of anodes and perhaps other vulnerable under water bits and pieces such as sail drives.

However, as LK says above, if the shorepower earth is not bonded to the internal "ground"/ DC negative/ anodes it is not necessary.

 

[Vara]

If you leave the shore-power connected ... that's connected, not necessarily in use, ... then a galvanic isolator is next to essential to prevent excessive rate of corrosion of anodes and perhaps other vulnerable under water bits and pieces such as sail drives.

However, as LK says above, if the shorepower earth is not bonded to the internal "ground"/ DC negative/ anodes it is not necessary.

How can you tell if SP earth is grounded to DC negative, on my set up a visual examination reveals no connection, would a continuity check DC neg to 3 pin earth show it up?

 

[rogerthebodger]

"However, as LK says above, if the shorepower earth is not bonded to the internal "ground"/ DC negative/ anodes it is not necessary"

A good reason not to bond AC earth to DC negative IMHO.

 

[superheat6k]

A simple DC ohmmeter will soon indicate if your bonding circuit is grounded to your AC earth.

If so the device shown may help. It is an active GI, not an indicator. It works by putting two groups of two large capacity diodes in series with each group in parallel and with opposite polarity. This presents a block to any DC voltage at the galvanic level, but high voltage AC earth leakage voltage / current can pass virtually unimpeded, maintaining safe earth grounding for the AC system.

Even with a GI my boat still likes the anodes so his year I have a substantial piece if zinc dangling between the boat and pontoon to try to reduce the hit on the installed anodes. This is connected to the earth ground bonding circuit boat side of the GI.

Ths time next year I will leave a thread if this reduces the anode wear.

The GI must be at least as large a rating as your main AC supply capacity.