Seeing how this is an electrical 101 thread I’ll add to it.
I bought a “new to me” boat in October 2013. During the two day transit from Boston to Narragansett Bay two things happened. At one point the first day I noticed the instruments and autopilot went dead. I went below and started checking things and they came back on after touching a wire. (first clue). We docked overnight and when we set out the next morning the alternator fried. At the time I thought it was some sort of back feed from the shore power that caused the alternator issue. (second clue). Fast forward to now, having the alternator repaired, $150 I asked what could have caused the failure and universally it was bad batteries. Now, having inspected the entire system the one thing that links both problems is a poor battery connection and sure enough the connections at the batteries were all dirty and corroded. Bad connection, no power to the instruments, bad connection no place for the alternator energy, fried diodes. I should have known from years of auto repairs that the first place to trouble shoot car electrical issues is at the battery connection. Lesson learned.
John
I bought a “new to me” boat in October 2013. During the two day transit from Boston to Narragansett Bay two things happened. At one point the first day I noticed the instruments and autopilot went dead. I went below and started checking things and they came back on after touching a wire. (first clue). We docked overnight and when we set out the next morning the alternator fried. At the time I thought it was some sort of back feed from the shore power that caused the alternator issue. (second clue). Fast forward to now, having the alternator repaired, $150 I asked what could have caused the failure and universally it was bad batteries. Now, having inspected the entire system the one thing that links both problems is a poor battery connection and sure enough the connections at the batteries were all dirty and corroded. Bad connection, no power to the instruments, bad connection no place for the alternator energy, fried diodes. I should have known from years of auto repairs that the first place to trouble shoot car electrical issues is at the battery connection. Lesson learned.
John
