Troubleshooting

Design Origins and Service Providers

The Duffy Classic propulsion system is based upon those used in golf carts. Many of the same parts, services, and tips & tricks apply. If you're having trouble diagnosing a propulsion system problem, try including the search term "golf cart".

When looking for service providers, an electric motor or golf cart service provider may be a good resource.

General Guidelines

  • Mechanical components fail much more frequently than purely electronic components, especially in a marine environment. Check connections, contactors, switches, and the potentiometer before assuming that a purely electronic component, such as the motor controller, has failed.
  • When troubleshooting issues with the motor, keep in mind that the motor controller will fail-safe by turning off the motor if it receives an input it doesn't expect or which is unsafe.

Common Problems

Motor periodically stops without a change in throttle setting. Moving the throttle to "Off", then forward/reverse often temporarily resolves the problem.

Common Causes:

    Motor controller is failing safe due to an unexpected or unsafe input. This could be caused by:
  • Dead spot or high resistance within the throttle potentiometer, sending an inconsistent speed signal (most common)
  • Intermittent signal from forward/reverse limit switch
  • Poor connection between the throttle and Infaspeed motor control enclosure

Tests

Intermittent problems are hard to measure at a given time. It is best to test when the failure is occuring.

  1. The diagnostic LEDs on the Infaspeed enclosure should always match key switch and throttle settings. If not, there is either a connection or component failure upstream of the Infaspeed enclosure.
  2. Measure the potentiometer speed signal at the connector to the Infaspeed enclosure. There should be a consistent 5-0 Ohm signal throughout the range of throttle inputs in either forward or reverse. If there is a momentary drop in signal, the motor controller will shut the motor off. It is difficult to measure this, so replacement of the potentiometer is a good approach if other potential causes are eliminated.
  3. If the motor controller diagnostic lights consistently match throttle inputs, one or more contactors may be working intermittently.

Power rapidly degrades while motoring

Common Causes:

  • Batteries (most common)
  • Poor high voltage connection(s)

Tests

  1. Battery energy gauge (Volt meter) on the instrument panel will show low or rapidly degrading voltage when when boat is at full throttle if either batteries are unable to provide the required power (most likely) or poor connections are adding resistance to the motor power supply.
  2. Check battery charger. There are usually lights on the charger that indicate charging status.
  3. Check battery charge and specific gravity, focusing on batteries that supply 12V to the key switch, which should be weakest.
  4. Check high voltage connections by using a meter to find potential voltage drops.

Motor operates in one direction, but not the other.

Common Causes:

  • Forward/Reverse contactor failure.
  • Failure of Forward/Reverse signal from throttle.

Tests

  • Check diagnostic LEDs on the Infaspeed enclosure to see if the contactors are receiving the correct signals.
    • If the correct signals are being received, inspect the forward/reverse contactors. There may be high resistance or a contactor may be stuck in a closed position (contacts fused).
      Contactors should be expected to fail with time and use. Your Duffy is older and has likely had contactors replaced at some point, often with cheap components that will not last as long as the original components.
    • If the correct signals are not being received, the problem is up stream at a connection or within the throttle (potentiometer or switches).

Two or more devices must be turned on before either work.
Example: Interior lights will only work when navigation lights are on.

Common Causes:

  • Poor ground connection(s). A circuit may be finding a new path to ground when another device is switched on. Ground wires often are connected to other grounds, especially as the boat is modified over time. This leads to a build-up of resistance where a weak point will eventually be exposed as corrosion occurs.

Tests

  • Check for poor ground connections in the affected circuits.

Turning on an accessory (e.g. navigation lights) causes your motor to stop or another system to degrade.
Examples: Motor stops working when the horn is on. Interior lights dim when navigation lights are on.

Common Causes:

  • Poor electrical connection(s) across a shared circuit. A device is drawing enough power across a bad connection to cause an excessive voltage drop. In the case of a motor failure, the motor could be receiving an unexpected signal and will fail safe.

Tests

  • Check for poor connections in the affected circuit.

Decrease in motor power and motor may operate erratically.

Common Causes:

  • Poor motor brush to commutator connection

Tests

  1. Check for excessive sparking in the brush area or unusual noises when under way.
  2. Inspection of the brush and commutator system.