Propulsion System Overview

The information provided is for 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.

Note: High voltage DC is shown as a thick line. 12VDC is shown as a thin line.

Batteries

DC power is provided by a bank of 6V batteries configured to provide either 36V, 48V or 96V to drive the motor. These batteries are tapped to also provide 12V for accessories.

Key Switch

The key switch on the console enables most systems to function. Exceptions are the bilge system and charging system, which are wired independently.

Throttle

The throttle sends signals to the motor controller that command what the motor should do. It has two limit switches that define the desired state (off/forward/reverse). It also has a potentiometer that sends a range of high to low resistance to define the relative amount of motor power (0 - 100%) desired.

Motor Controller

The motor controller is a programmable electronic device that interprets signals from the throttle to safely and efficiently control operation of the motor. It conditions high voltage inputs to safely and efficiently drive the motor.

Main Contactor

The main contactor closes when it receives a 12V input from the motor controller, sending high voltage power to the motor controller.

Forward & Reverse Contactors

These are two contactors that act together to control the polarity of power sent to the motor in order to control motor rotation direction.

Motor

This is a DC Series motor that drives the propeller shaft and propeller via a drive belt.

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