30 SECOND BRIEFING:

LITHIUM ION BATTERIES

Safe bet It isn’t mandatory to use lithium batteries to power an electric or hybrid boat; standard lead batteries can be made to work as long as the output voltages generated match the needs of the electric motor to be powered. However, so numerous are the advantages of lithium batteries that it’s crazy to use anything else unless financial considerations unequivocally dictate otherwise. ● Weight and bulk The power density of lithium batteries is far higher (at least double, but typically more), so it’s not just weight but also sheer physical bulk that will often rule out the use of ‘normal’ batteries on electric boats. ● High-current capacity Lithium batteries’ high-current capacity makes them more agreeable to the demands of an electric motor. They exhibit practically no memory effect, so the repeated charge and discharge cycles that electric/ hybrid boat batteries experience do not present a problem. However, they do typically lose 4% of their capacity per year. ● Waterproof to 1m The better lithium ion batteries will use individual steel safety cells rather than foil-sealed cells to enhance the higher levels of safety necessary for lithium-based installations. With safety in mind, Torqeedo’s batteries are all waterproof to IP67, i.e. 30 minutes immersion at 1m depth. ● Safety features Other Torqeedo battery safety features include a water sensor which will also shut down the battery if it detects submersion. Intelligent on-board circuitry with a full BMS (battery management system) constantly monitors for overheating, short circuits, overcharging, and overcurrent draw. The BMS is able to shut down the battery completely in the event of a problem, or simply to transport the battery safely.