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Electrical System Overview

Our boat is a 2002 Duffy 18' Classic. Many systems and components are common across models and years.
It is up to you to determine if this information applies to your boat or not.

Power

Power comes from two sources:

1. Shore Power

   120V from the cable connected from the dock to your boat.

2. Batteries

   A combination of 6V batteries connected to provide both high and low voltage DC.

From these two sources, there are three electrical systems on the boat:

1. Shore Power (120V AC)

   Generally used only for the battery charging system, though there was an optional 120V window defogger accessory that could be installed under the Port step/storage compartment.

2. High Voltage DC (36-96V DC)

   For powering the propulsion system, the battery volt meter, and optional cabin heaters. Duffy offered 36V, 48V or 96V configurations for several power and endurance options. Example configurations can be found in the Batteries and Battery Configurations section.

3. Low Voltage DC (12V DC)

   For powering all other systems. 12V is provided by tapping pairs of 6V batteries that are wired in series. There are usually multiple pairs of batteries tapped to feed different 12V systems.

Distribution

There are no common buses or circuit breaker panels. Instead, you will find:

• The key switch feeds +12V to a series of circuit breakers and switches next to it on the instrument panel.
• Other systems are powered by taps on the battery banks, (e.g. volt meter, bilge pump, key switch, 12V accessory outlet, propulsion system, charging...) or from the key switch circuit. These should each have their own circuit protection devices.
• A small ground bus in the motor compartment serves several systems, but most grounds are distributed.

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