Isolated Earth Alternators?

Discussion in 'OnBoard Electronics & Controls' started by powerabout, Jul 26, 2011.

  1. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    What your view on isolated earth alternators, jap and european engine marinisers seem to use them and US ones usually dont?
     
  2. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 33, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    presumably they want to wire the house system insulated return and put the starting battery with its own alternator next the engine doing only that job.
    presumably the yanks have decieided its not worth the effort/cost and the only things which need them by law are petrol tankers ...
     
  3. goboatingnow
    Joined: Oct 2008
    Posts: 65
    Likes: 4, Points: 0, Legacy Rep: 74
    Location: Ireland

    goboatingnow Junior Member

    Why dump DC negative transients through the block when you don't need to. If you have access to a isolated DC negative, then it's a better solution

    Dave
     
  4. DGreenwood
    Joined: Aug 2004
    Posts: 714
    Likes: 34, Points: 28, Legacy Rep: 507
    Location: New York

    DGreenwood Senior Member

    I am a yank and I always build them isolated if I can and recommend to owners that don't have it, to change it over. If sending units do not have a double pole setup then it is kind of moot isn't it? That is the second part of the that PITA to change over.
     
  5. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    correct
    but who ever changed a block out because the charging earth ran through it to the neg battery terminal and damaged it?
     
  6. DGreenwood
    Joined: Aug 2004
    Posts: 714
    Likes: 34, Points: 28, Legacy Rep: 507
    Location: New York

    DGreenwood Senior Member

    Huh?...You only need to change the alternator and sending units.
     
  7. BertKu
    Joined: May 2009
    Posts: 2,429
    Likes: 38, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    The advantage is that one can then have 2 alternators running on the diesel and have the 12 Volt and 24 Volt batteries charged.
    Bert
     
  8. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    you dont need isolated earth to do that.

    So whats the problem you are solving with isolated earth?
     
  9. goboatingnow
    Joined: Oct 2008
    Posts: 65
    Likes: 4, Points: 0, Legacy Rep: 74
    Location: Ireland

    goboatingnow Junior Member

    Impressed current corrosion.
     
  10. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    How will you notice that is happening to your engine?
     
  11. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 114, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Corrosion in Exhaust system, pumpshafts, heat exchangers...anything wet.
     
  12. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Michael
    Whats the physics of that, what is the circuit that is running via the sea water ( other than normal 2 dissimilar metals in an electrolyte) that involves the negative/earth of the battery/alternator
     
  13. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 114, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    How do you know that the current is negative ?
     
  14. powerabout
    Joined: Nov 2007
    Posts: 2,901
    Likes: 61, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    cant find any info on that
    but plenty of corrosion protection systems by using Impressed current
     

  15. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 114, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Yes indeed..it is possible to deploy an impressed current corrosion protection system. I have used them...not cheap...and they must be constantly monitored.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.