In Part 1 we learned that it was inefficient, and often impossible, as well as potentially dangerous, to supply the high-load equipment, that so many cruisers seem to want, with a 12-volt system. And, further, that the solution to this problem is either to forgo all very high-current (amperage) gear, or select a boat with a 24-volt system. So let’s look at that.

So which is better, 12 or 24-volt DC systems for live-aboard cruising? Like most things, it depends. Here’s a definitive way to determine which is best for your boat and usage.

These days we are seeing more and more gear added to boats, much of it AC supplied through inverters from the battery, that demands current (amperage) way higher than even dreamed of a decade ago. But will our electrical system buckle under the load? Here’s how to figure that out ahead of time.

An analysis for any live-aboard cruiser who is considering a lifestyle that will require more than about 250 amp-hours at 12 volts (3 kWh) of electricity daily.