Hiroshima, Japan – Mazda has announced the world’s first passenger vehicle regenerative braking system that uses a capacitor rather than a storage battery. Called i-ELOOP, the system will begin to appear in Mazda vehicles in 2012.

The company said that in real-world driving conditions with frequent acceleration and braking, i-ELOOP improves fuel economy by approximately 10 per cent.

The capacitor is an electrical component that temporarily stores large volumes of electricity. Unlike batteries, capacitors can be charged and discharged rapidly and are resistant to deterioration over prolonged use. The i-ELOOP system converts the vehicle’s kinetic energy into electricity as it decelerates and uses the electricity to power the climate control, audio system and numerous other electrical components.

Regenerative braking systems, which are becoming popular as a fuel-saving technology, use an electric motor or alternator to generate electricity as the vehicle decelerates, recovering a portion of its kinetic energy. In hybrids, the systems generally use a large electric motor and dedicated battery.

The Mazda system uses a new 12-25V variable voltage alternator, low-resistance electric double-layer capacitor (EDLC), and a DC/DC converter. It starts to recover kinetic energy as soon as the driver lifts off the accelerator pedal and the vehicle begins to decelerate. The variable voltage alternator generates electricity and sends it to the EDLC for storage. The capacitor, which has been specially developed for vehicle use, can be fully charged in seconds. The DC/DC converter steps down the electricity from 25 to 12 volts before it is distributed directly to the vehicle’s electrical components. The system also charges the vehicle’s battery when necessary.

The i-ELOOP system operates whenever the vehicle decelerates, reducing the need for the engine to burn extra fuel to generate electricity. It also works in conjunction with Mazda’s idle-stop technology to extend the period that the engine can be shut off.

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