Batteries power underwater vehicle

A new Li-ion battery system will provide the Redermor experimental underwater vehicle with up to five hours of autonomous power for its electric thrusters and onboard electronics.

Saft has been awarded a contract by GESMA (Groupe d'Etudes Sous Marines de l'Atlantique) to develop a rechargeable lithium-ion (Li-ion) battery system that will significantly boost the performance and payload capacity of the Redermor experimental UUV (Unmanned Underwater Vehicle) platform.

The new Li-ion battery system will provide Redermor with up to five hours of autonomous power for its electric thrusters and onboard electronics.

Housed in a compact, maintenance-free module, the new battery system is just half the size of the batteries fitted to previous Redermors.

GESMA developed the Redermor UUV in the 1990s as an experimental platform used for evaluation of data acquisition and acoustic communications technologies for detecting and identifying underwater mines.

Redermor is now operated as a fully autonomous free-swimming vehicle, it is 6m long, about 1m diameter and weighs between 2.7 to 3.2 tonnes, depending on the version.

Eight electric thrusters allow the Redermor to be very manoeuvrable and to travel at speeds of up to 10 knots at depths down to 200m.

It is also designed to carry large payloads (about one tonne and 1m3) such as high-resolution sonar and large range of sensors.

Redermor is powered by a 260V onboard battery.

When designing the new version (Redermor-3), GESMA selected Saft's Li-ion technology in order to drastically reduce the size of the battery while maintaining the same performance and also to have an easy to operate and maintenance-free subsystem.

The reduced size will enable the operator to increase the equipment payload or to add another high-power battery pack to double Redermor's endurance.

The Redermor-3 battery system is based on Saft's VL45E Li-ion cells, originally developed for hybrid and electric vehicle applications to pack maximum energy into a lightweight and space efficient package.

The battery system needs no maintenance has a low auto discharge and offers excellent reliability through its long operational lifetime.

Saft will integrate these cells into a custom-built module, designed to make the best possible usage of the limited available space.

The battery pack also include an electronic control management system for the monitoring of charge and discharge voltages and cell temperatures.

The battery system is scheduled for delivery to GESMA in September 2007.

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