Saft High Energy rechargeable lithium-ion batteries, originally designed to power electric vehicles, are now taking to the waves in the new generation of Delfjet electric jet-propelled water scooters. The Delfjet concept was developed in Germany by Jurgen Grimmeisen, who wanted a watersports machine capable of pulling a swimmer with high speed and dolphin like manoeuvrability both on the water surface and below it. As well as great potential in the sports and leisure market, the machine will have more serious applications, such as in lifeguard duty on beaches.
The unit is propelled by a silent, Newtor brushless 42V electric motor which was originally powered by conventional nickel cadmium batteries. The low endurance (25Ah capacity) and high weight (35kg) of these batteries was a problem as the design weight of the Delfjet without batteries is just 16kg. Saft offered the alternative of high-energy lithium-ion cells which have a nominal capacity of 43Ah and a nominal voltage of 3.6V. This enables a 42V battery to be constructed using just 12 cells in series, with a total weight of 12kg, virtually doubling the battery capacity at around one third of the weight, and in a much smaller volume.