New 48 Volt electric boat motor uses ‘Virtual Gearbox’

This new 48 volt electric boat motor from Volabo (Ed’s Note: The company name was changed to Molabo in late 2020) uses ISCAD – which stands for Intelligent Stator CAge Drive – to create a virtual gearbox as an integral part of the 50kW system.

Unlike most electric motors, which use permanent magnets or electrified wound coils of copper to create the magnetic poles and fields that make a motor spin, the Volabo ISCAD uses aluminum bars that make up a ‘cage’ (see left) in which different bars can be paired to create a varying number of magnetic poles. The fewer the paired poles, the faster the motor turns, (see gif below) and there is also a corresponding change in the torque of the motor.

Motors with permanent magnets or wound coils need to have the number of pairings established beforehand, meaning that there is one pre-determined optimum efficiency, RPM rate and torque. The realities of use, though, mean that the demand on a motor for something like getting a boat on plane versus the demand of running at a constant speed are different. The motor designers pick something that is the best balance between the two but isn’t the best for either use.

With the ISCAD innovation the motor can adjust to the type of load required at the time and provide the best speed and torque for the task. The other essential part of the system, aside from the aluminum bars and the pole pairings, is an electronics system that decides when the pairings should be changed.

48 volt electric boat motor provides 50kW power

The ISCAD system provides a number of benefits, not the least of which is that high drive power can be provided using a very safe voltage level of only 48 volts.

The company worked with My-Electroboot to demonstrate a 50kW motor (67 HP) on a 22 foot (6.7 metre) boat at Austria’s Tulln Boat Show in early March. That 50kW of power is important, because If you look at our Plugboats Guide to Electric Outboards over 5kW, you’ll see that electric boat motors typically start to jump to voltages above 48V at the 20 or 25 kW power level.

Adrian Patzak, one of the co-founders of Volabo, said “We didn’t want to offer another 48 volt drive for small outputs. We wanted to start right away where it is currently only possible to electrify a boat with high-voltage systems.” Patzak and the other co-founder, Florian Bachheibl, have been developing the motor since the ISCAD concept was introduced to them by Professor Dieter Gerling, Dr-Ing when they were students at Munich’s University of Federal Defense.

It was in January 0f 2013 when they began to develop the stator cage idea and the team was awarded its first patent in April of 2014. Since then they have been granted 7 more and have 45 applications worldwide. They presented their first paper at the International Electric Vehicle Conference in December and by July 2015 had a prototype working, although it was low power and the electronics controlling the pole pairing needed to be cooled in a refrigerator separate from the motor!

Large investment to develop electric boat motors

I wasn’t until 2016 that Volabo (which means ‘fly’ in Latin) was incorporated as a company. Later that year it delivered Prototype #2 followed by #3 in September of 2017 – a 100kW stator cage motor powerful and compact enough to be tested in a VW Touran a year later.

It is the 4th generation of the motor, the V50 ISCAD, that is installed in the My-Elektroboote. The V50 was unveiled in late January of this year along with the announcement of ‘a seven-digit (Euros) Series A financing round’ from the Hechinger group of companies. Hechinger is bi in the automotive and electronics sectors and the investment is pegged for boat and marine Volabo product development.

The compact size and weight of the V50 ISCAD makes it a very attractive option for boats. The motor is only 299 mm (11.75″) in diameter, 490 mm (20″) long and weighs in at 60kg / 132 pounds. That size and weight includes the controller.

The first demonstration boat uses the motor as an inboard and shaft configuration, but there are also plans to have the ISCAD available in every option: saildrive/pod, outboard, and Z Drive (sterndrive – inboard/outboard). The company says that a new, smaller motor is under development that will be only 240 mm in diameter and 250 mm long: 9.5″ x 10″.

While the main advantage of the Volabo technology is that high power ratings can be achieved using a 48 volt battery, there are also differences in the construction process that make the Volabo significantly cheaper to build. A big part of a regular electric motor is the copper coil windings, which can be as much as 40% of the overall cost. Using aluminum bars and eliminating other parts of a traditional motor mean the Volabo can be manufactured for about 20% less overall.