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Intermittent 12V draw-gctid409549

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    Intermittent 12V draw-gctid409549

    For as long as I've owned my 285 (since 2003) I've noticed an intermittent draw on the 12V system.

    Sometimes every minute or so, sometimes longer, the lights dim and fans slow for a second or less. Then back to full brightness.

    I hate the fact that the 12V circuit breakers can't be manually tripped. They're the little pushbuttons in the plastic bubble, and pushing one that's closed doesn't open it.

    So to systematically disconnect everything, one at a time, will take some effort.

    I was wondering if anyone else has (1) had this same issue, and (2) tracked down the culprit.

    My first guess was the fridge, but even with that off line the symptom persists. The CO alarms are my next guess, followed by the Mercathode system. All permanently wired in.


    Does it happen on shorepower or both ?


      3 wide wrote:
      Does it happen on shorepower or both ?
      +1 Yeah - need to know this first.

      My initial thought was the charger (acting as a converter) kicking on/off.

      Potable water pump is another 12VDC load that cycles (on a pressure switch).


        Whether shore power connected or disconnected makes no difference.

        The potable water pump is loud enough that I'd notice it cycling. That's happened a few times when I left a faucet dripping, so I know what it sounds like.

        None of the bilge pumps are the automatic type that come on periodically to check for water.

        Doesn't matter whether the engine is running or not.

        Clearly, something is causing a large but very brief drain on the 12V side.


          I haven't experienced this on my boat, but if it happens with or without shorepower, that eliminates anything that runs only on shore power, like, stove, microwave, charger, outlets. Of what's left, the big 12 volt draws I've seen would be #1, windlass, fresh water pump, then maybe fridge running on 12 volt, possibly TV. All of those are likely things you would hear (unless music is always being played). Beyond that, I don't know what draws enough to make a noticeable dimming of lights.

          2008 Rinker 330 EC
          Twin 350 MAG Bravo 3
          2007 285 (sold)
          350 Horizon Bravo 3