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Shorepack high voltage problem

Discussion in 'Electronics' started by jflongwell, Apr 14, 2010.

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  1. jflongwell

    jflongwell Member

    Joined:
    Aug 27, 2008
    Messages:
    57
    Location:
    Watkins Glen on Seneca Lake
    I had a problem with the Shorepack unit for the Capac cathodic protection (aluminum hull). The boat is on blocks out of the water. I was connecting the batteries and noticed sparking when connecting the wires. I checked the voltage and found I had 20 volts!
    Traced this to the Shorepack (AC was on). Turned the AC off and disconnected all the batteries. After turning the AC back on, the voltage was back to normal (14).
    Thoughts? The Shorepack uses a vacuum tube! Are these fixable?
    John
  2. K1W1

    K1W1 Senior Member

    Joined:
    Sep 30, 2005
    Messages:
    7,388
    Location:
    My Office
    Hi,

    Do you have the CAPAC Unit running while you are up on blocks?
  3. jflongwell

    jflongwell Member

    Joined:
    Aug 27, 2008
    Messages:
    57
    Location:
    Watkins Glen on Seneca Lake
    CPAC unit

    I had removed the fuse from the CAPAC. When I replaced the fuse, the voltage dropped to about 14. The AC feed is directly to the Shorepac after the isolator. I was able to find the wiring diagram for the boat, but am faced with 40 years of "updates" that are not included. Is there a way to turn this off when on blocks?

    I am concerned this current is toasting my battery. I replaced the Ray Jefferson battery guard with a newer unit that adjusts the current depending upon the battery's condition. Would a diode in the DC connection to the battery be a good idea? It would allow current to flow to the Shorepac when there is no AC, but prevent flow to the batteries.

    Thanks

    John
  4. Marmot

    Marmot Senior Member

    Joined:
    May 20, 2007
    Messages:
    3,311
    Location:
    9114 S. Central Ave
    You might want to take voltage readings with a good old fashioned analog meter like a Simpson 260 if you can find one. High impedance digital voltmeters often read stray voltage and noise that can confuse things when you are working on power circuits.