Since the establishment of Torqeedo, we have not only produced electric motors for boats but also complete electric propulsion systems. In other words, in addition to motors, batteries and control systems, we have worked intensively on intelligent communications between the individual components and simple, informative user interfaces since our foundation. One of the best examples is the on-board computer of our Travel. Each Travel is equipped with four different micro-controllers:
- one in the pylon for commutation,
- one in the battery for the battery management system,
- a complete GPS system, also installed in the battery, and
- one in the tiller.
If a Cruise is combined with a Power 26-104, there are even five micro-controllers. The intelligent shaft-head circuit board of the Cruise also performs current measurements and battery status calculations for "stupid" lead-acid batteries.
Each of these controllers provides a wealth of data on the condition of the relevant subsystem, such as torque, speed, battery charge, charging or discharging current, position, temperature and many different error codes for self-diagnosis, etc. These data are merged to give the user an indication of the current status of the propulsion system. For this purpose, a display providing real-time information on the following values is integrated in the tiller or remote throttle unit:
- Battery charge status
a. charge in % of capacity or
b. battery voltage
- Remaining range (at current speed and current in km, miles or nautical miles)
- Speed over ground (in km/h, miles per hour and knots)
- Input power (in watts)
In addition, the display indicates when the motor or battery switches to the temperature protection mode and provides warnings and a variety of error codes for self-diagnosis if a problem occurs.
The most important value is the remaining range, which indicates whether the boat can reach the desired destination with the charge that is available, at the speed travelled under present conditions (wind, current conditions, etc.). If the remaining range is insufficient, it can be increased quite easily by slowing down slightly. As drag increases quadratically with increasing speed, the remaining range in displacement mode can be quadrupled by halving the speed. In other words, even a slightly lower speed significantly increases the range available. The calculation of remaining range is also a good example of the need to use a holistic approach to developing marine propulsion systems. It is only by combining the power currently taken by the motor P in Watt, the remaining energy stored in the battery E in Wh and the speed over ground v from the GPS in km/h that the remaining range in km can be calculated by