Voltage Regulation

We've been at this blogging for a couple of months now, and while Michelle always talks about the joys of sailing, I seem to be the person talking about the maintenance problems. I guess that's just a reflection of my being part-time grease monkey.

The first year of boat ownership involved a steep learning curve. We've talked before about problems with our roller furler and electical connections. Another problem we had was with our power supply.

For those not overly familiar with boats, there are generally two power systems. One is the standard AC system, which you access by plugging your boat into the power outlet on the dock. The second is the 12 Volt DC system, which is similar to a car system. It is powered by a pair of batteries if the engine is off, or by the engine itself through an alternator when the motor is running. This is the system that operates most of the on-board electronics, such as the radio and depth sounder.

During the first year, we had lots of problems with these electronics. We chalked it up to the age of the systems - after all, it is a 20 year old boat. After the first year, we decided to replace the VHF radio (which worked intermittetly) and the depth sounder (which had stopped working altogether). At the start of year 2, I replaced these components before the boat went into the water.

Our first trip out, we noticed that the new depth sounder seemed to be having problems. It would shut off intermittently for no apparent reason. I pulled out more than a few hairs trying to find out where the bad electrical connection was. After resplicing all the wires, Michelle noticed a funny symbol on our new radio. Looking this up in the manual, it was a symbol denoting that there was too much voltage. Sure enough, we measure it and there was 17 volts going through the system - enough to cause lots of electrical problems.

So, being totally inexperienced in this sort of matter, we asked around, and the consensus was that this is a problem with the voltage regulator on the engine letting too much voltage into the system. So, I pulled off the alternator and brought it to a shop for testing. They said it was fine. Put it back on the boat - same problem. Lots more troubleshooting, recruiting a couple of peole to help me, and we thought that we found a problem with a ground. Put everything back together, and it works. For five minutes, then the problem reappears, so it wasn't the ground.

At this point, everyone is out of other ideas, so we took the alternator off again, and brought it to a different shop for testing. Again no problems, and a third shop found no problems. At this point, I gave up and bought a new alternator and installed it. The voltage was then fine, so the alternator was obviously the source of the problem.

I still have no explanation for why the alternator repeatedly showed no voltage regulation problems when it was tested. The only shops on PEI are automobile electrical shops, so maybe there is some operating condition on the boat that they are not able to replicate. But this adventure took over two weeks to solve, and we had to cancel a planned trip to Shediac because of it.

But, on the plus side, we now have a nice new DSC radio, depth sounder and wind instrument out of the whole process.