Norm shares another valuable lesson learned from a major electrical system failure while on passage in the South Pacific. Today’s boats having more and more electrical devices aboard. Failure of the boat’s electrical system can create havoc ranging from spoiling all provisions in the freezer to the loss of key navigation and communication systems.
We had just started our passage from Niue to Tonga, a distance of 325 nautical miles. The weather was stormy and overcast so the solar panels were not generating any power. We thought it would be a good idea to motor sail for a few hours in the late afternoon to charge the batteries before going into the night. We always like to have good battery reserves for operation of the radar. We were surprised to see that the battery charge status did not improve after an hour of motoring. A close inspection showed the alternator had no power output. It was not charging our batteries at all!
Our immediate response was to reduce our power consumption so we could save whatever juice still remained in the battery for navigation and communication. We shut down the refrigeration and everything but essential navigation equipment. The remaining power in the 800 amp hour battery bank was adequate to get us to our landfall without incident. Fortunately it was a short passage. Upon arrival in Tonga the sun came out providing more than enough solar power for all our needs at anchor. Our problem was solved but only for the short term.
My assumption was the alternator had failed. We carry an identical spare. I would just swap alternators and then go for a snorkel. When this did not make any difference I concluded the problem must be a regulator failure. We carry a spare one of these as well. I swapped the regulator but this too made no difference. There would be no snorkelling this day. The next step was to try replacing both the alternator and the regulator on the off chance both had failed simultaneously. Still no output. I then turned my attention to the wiring harness and checked that every connection was still in place. They were all intact.
This is when I gave up and called for help from other cruisers in the anchorage. There were many volunteers with various degrees of expertise. Most swaggered onto our boat confident they would quickly find the problem. All of them departed mystified and with egos somewhat deflated.
I then decided to test the continuity of every single wire in the wiring harness, checking the resistance from one end to the other to make sure there were no hidden breaks anywhere. Mark Aisbett on s/v Merkava, a BCA member, helped me with this painstaking process. We soon discovered that corrosion inside one little spade connector on one control wire was responsible for shutting down the whole system. A new connector was crimped on and the problem was solved.
I immediately assumed the charging problem was due to the failure of a major component like the alternator or regulator. But these components are generally pretty robust. The problem lay in the connectors. The humid salt air in the tropics eats away at all electrical connections, particularly crimped connectors that are often exposed to the air. This is the first thing I should have checked, not the last.
Always Suspect Corrosion in Connectors: Most electrical failures in the tropics are due to corrosion at the terminals, connectors or crimps. Check these first before replacing components.
Have Diagnostic Tools: Have a good multimeter with a continuity tester. Know how to use the ohmmeter function to measure resistance. Have a long length of wire you can stretch throughout the boat to make certain tests. Have several sets of alligator clips.
Contact Cleaning Solution & Fine Sandpaper: Surface corrosion that is invisible to the eye can build up on connectors and create resistance. Often all that is required to solve a problem is to clean the contacts with spray contact cleaner and/or use a little fine sandpaper.
Carry Spare Connectors, Crimpers & Wires: Sooner or later you will have to replace electrical connectors on your boat. Your spare parts box should have a large selection of proper marine grade connectors of every shape and size, a set of quality crimping pliers and a good supply of marine gauge wire of various gauges. Corrosion can wick its way up inside the wire from the connector rendering much of it useless. Then the wire run must be replaced.
Protect Against Moisture Penetration: If possible use heat shrink and/or connectors with integrated heat shrink covering to minimize moisture penetration. A heat gun works great on shrink wrap provided your inverter can handle the load.
In this case a new connector, crimped onto the end of one of the alternator control wires, solved the problem. The spare alternator and regulator went back into their storage boxes.
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