Electrical System Overview

Power

  1. Shore Power (120V AC)

    120V AC is supplied by your shore power connection to your boat. It is primarily used for powering the battery charger.
    An optional 120VAC window defogger maybe be installed in the Port step storage compartment.

  2. High Voltage DC (36-48V DC)

    This powers the propulsion system, the battery volt meter, and optional cabin heaters.

  3. Low Voltage DC (12V DC)

    This powers all other systems, such as lighting, accessories, control circuits. 12V is provided by tapping some of the batteries used for the high voltage DC system.

Duffy Power Sources

This diagram shows one source for 12V and one for 36V. In reality, there are likely multiple taps for different systems. For example, our boat had independent 36V connections for the motor, the cabin heaters, and the energy (Volt) meter. We also had independent 12V connections for the main key switch and panel, accessory outlet, and bilge pump.

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, 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.
Duffy Electrical System Overview