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Bird on a Wire

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While isolation transformers tend to be terribly dull, they are valuable.

Last summer I managed to cruise a snazzy, borrowed twin-screw flying-bridge boat from Maine to Connecticut. She was loaded with first-class, well-installed systems, most of which my relatively inexperienced crew and I learned to use pretty easily, contributing to a fine trip. The exception was the fairly conventional A.C./D.C. power setup—dual battery banks, inverter/charger, shore power, and genset—which vexed me. I never felt that I fully understood what was going on in this important department, and the facts that the house bank often wouldn’t charge underway without running the genset first, and that toasting a slice of bread—i.e., loading the inverter—knocked the autopilot compass out of whack didn’t help. But the specifics of that trip are another story. My point is that the trend toward smarter, more easily understood and managed electric power components is a welcome one indeed.

Which is why Lyle St. Romain’s boat-show pitch worked so well on me. St. Romain, a graduate of Raymarine and other marine electronics companies, now manages the marine division of Charles Industries and was standing in a booth piled with its various A.C./D.C. products when he proclaimed, “Man, these boxes are the last great mystery of boating!” He went on to explain that Charles was developing some “intelligent,” and hence demystifying, new products and invited me to his native New Orleans for a closer look.


Steve Karp

A break in the grounding circuit is just one of several ways A.C. current can wander dangerously.

Thus I found myself on Lake Pontchartrain last fall getting a thorough preview of Charles’ latest. The Intelligent Marine Charger series seemed to fulfill St. Romain’s promise and my expectations. The microprocessor-equipped IMcharger is not only smart about how it cares for multiple battery banks, but also informative about their condition. A clear and accurate on-deck display of bank voltages and remaining amp-hours would have been useful on that summer cruise, but actually there are many monitoring schemes that could provide this information, and Charles’ competitors (like Mastervolt, Xantrex, and Victron Energy) are all developing intelligent marine power systems. In fact, remote displays and controls are coming to all sorts of previously brain-dead boat gear, like fuel fills, tank valves, and bilge pumps.

However, the electronification of traditional gear is not the whole story. The new Charles product that really captured my attention doesn’t have a microprocessor, a screen, a network connection, or even an on/off switch! That plain white box is an ISO-G2 isolation transformer meant to protect a boat from various shore-power problems. It’s really just an extension of Charles’ already extensive line of such transformers (the G2 now being the smallest) suitable for a boat with only a single 30-amp A.C. connection. Even one this small costs about $770, and you’ll never know it’s on your boat except perhaps because of all the bad things that don’t happen. But a clear explanation by Charles’ engineer Larry Budd about what those possibilities are, plus some further research, was compelling.

This article originally appeared in the April 2007 issue of Power & Motoryacht magazine.