Alternator Chronicles

When things go wrong on a boat they can go very wrong.

It pains me a little that despite owning a sailboat and being a lover of the sailing aspect of owning a sailboat, since taking ownership of Shearwater, most of our effort, time, frustration, and a great deal of our funds have gone to the engine and drivetrain.  I don’t even like motors!  So far, we’ve replaced the prop, the prop shaft, the cutlass bearing, the shaft seal, the engine mounts, the alternator, the regulator, and emptied and cleaned the fuel tank, not to mention my issue with installing the Racor fuel filter with the o-rings swapped such that we had a perpetual air leak in the fuel system the day before we were planning to leave Annapolis.  Engines.  Hate ‘em.

Anyway, I mentioned in a daily update during our crossing that the alternator was not doing what I expected.  We never saw more than 80 amps out of the 120 amp alternator.  I wasn’t sure if that was normal, but it seemed low to me.  After we returned to Europe I started researching and sure enough it seems our 400Ah AGM batteries could probably accept 200 amps when discharged.

The little beast

Okay, there is likely an issue.  What is it?  When we returned to the boat recently to pick up the things we couldn’t carry on the plane to Madrid, I sat down to do a little investigating.  Pulled out the Balmar manuals and started going through the checks with the engine off, then with the ignition on, but the engine still off.  One voltage reading was a little off, but nothing alarming.  Oh, and it was so much easier this time to conduct these tests on a still, level boat.   Our weekend was almost over and it was just about time to head back to Madrid, so just one more check before we go.

Chris started the engine and immediately I knew there was a problem.  The voltage for the batteries went down instead of up and the lights on the regulator went out.  I asked Chris to shut down the engine, she pulled the stop lever, the engine slowed, but didn’t stop.  It continued to turn over!  She tried a few times.  I popped open the starboard engine access and physically pulled on the stop lever on the engine.  No change.  I tried sticking a rag over the air inlet, but couldn’t get a tight seal.  I’m going back and forth around the engine trying to figure how to stop the engine.  And that is when I notice the battery selector switch.  Instead of being on House the indicator is part way between House and Off.  I know enough about alternators to know that the battery switch should never be off with the alternator on or it will damage the alternator.  I quickly switch the selector back to House and about the same time smoke starts coming out of the alternator.  Not good.  Not good at all.

Chris is continuing to try the stop lever and moments later the engine rumbles to a halt.  So…  What just happened?  Well, it is clear the alternator is toast.  The 2 month old very expensive alternator that is.  The 250 amp slow blow fuse to the house batteries also blew.  Good thing we added that back in Annapolis as it probably prevented an ugly electrical fire and hopefully prevented damaged to our also new and expensive AGM batteries.  The battery monitor recorded a peak current of -310 amps coming OUT of the batteries!

Let me make this long story a little shorter.  The battery switch had nothing to do with anything.  Pure coincidence.  First of all, if the switch was truly Off the engine won’t start.  Second, I wired the alternator directly to the House lug on the back of the switch so the alternator would be unaffected even if the switch was turned to Off.  I believe that either A) the regulator failed internally B) the alternator failed internally or C) there is a short somewhere in the system that caused them to fail.  There is conflicting opinions, but it seems that the alternator while drawing huge current from the batteries was creating some type of generator/starter effect that was keeping the engine just barely running until it went up in a puff of smoke and the engine could shut down normally.  Balmar says that can’t happen, but the engine shut down normally every time before and after the alternator meltdown, so?

So, now what?  I contacted Balmar and they have been extremely helpful.  A new regulator and alternator at a reasonable cost have been shipped.  I’ll return the old parts and if either are found to be defective the cost of the new part will be refunded.  I’m not holding my breath on that, but it does ease the sting a little and the logistical hurdle that I expected to be a challenge was easily handled.

My hope is that the regulator failed causing the alternator to fail.  That voltage reading that was a little off before starting the engine points a little finger that the regulator might be the guilty party.  Either way, I need to go through the entire circuit looking for short circuits, loose connections, or corroded connections.  That may take awhile, but it is necessary to ensure we don’t blow up another alternator.

So, next time we visit the boat we’ll have a new alternator and regulator to install and with luck it will all work and we’ll also start getting more than 80 amps out of the alternator.  Here’s hoping.  I have a feeling we are a long way from the end of this story.

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