Torqeedo Cruise motor overhaul fault diagnosis

An owner of an existing electric sloop contacted Robust-MT Marine Technology BV regarding an acute malfunction. The vessel had not been delivered or maintained by our team at the time. The boat was equipped with a Torqeedo Cruise 4.0 electric motor. In practice, this motorization was actually undersized for the dimensions of the sloop. The power supply consisted of an older 48-volt setup. Two separate 24V Torqeedo lithium batteries were connected in series to provide the required voltage. Charging was performed via two separate 24V battery chargers. The current error message on the display pointed directly towards a critical voltage problem in the underwater-mounted motor pod. Robust-MT was commissioned to thoroughly investigate and resolve this complex communication and propulsion issue.

Extensive fault diagnosis in the workshop

This specific Torqeedo system utilizes a completely closed communication network between the throttle, the battery banks, and the motor unit. Without an active data link between all these components, the system refuses any form of charging or discharging. As a result, it was technically impossible to test the chargers and batteries separately on the workbench. Furthermore, the motor lock in the boat turned out to be stuck fast due to rust formation. To establish a reliable diagnosis, our engineering team in Monster followed the following procedure:

Test setup with reference material

We had a functional 24V Torqeedo motor from another customer brought to our workshop. We built a closed test circuit with this temporary reference motor.

Excluding components

Thanks to this setup, we were able to extensively test both 24V batteries and both battery chargers in all conceivable combinations. No errors occurred during this process. This confirmed that the energy storage and the charging infrastructure were fully intact.

Disassembly of the drive

After removing the rusted engine lock, we dismantled the engine and the electronic throttle from the sloop for further examination.

The technical solution and revision

Upon opening the disassembled motor pod, our specialists encountered severe internal contamination. After thorough technical consultation with the official importer, we determined that there was a double defect: active water ingress through the shaft seals combined with detached magnets on the rotor.

To ensure a perfectly high-quality repair, we sent the motor pod directly to the importer for a complete factory overhaul. This specialized process entailed significant lead time and additional overhaul costs. Following formal approval from the client, the overhaul was expertly executed. One day after the overhauled parts arrived at our workshop, our team reinstalled the complete drivetrain, including the overhauled motor pod, throttle, and data cabling, in a vibration-free manner. Subsequently, all electrical circuits were successfully calibrated.

Result

The complex fault diagnosis and subsequent engine overhaul have been successfully completed. After the final system test in the water, the complete 48V Torqeedo Cruise installation was functioning fully fault-free and within factory specifications again. The error messages have been permanently resolved and the power supply is stable once more. The customer was able to take delivery of the boat immediately at our harbor and successfully sailed to their home port under its own power the same day. This project demonstrates that Robust-MT possesses the right in-house diagnostic expertise to guarantee a reliable result, even for complex data faults in closed systems.