Mazda i-ELOOP : innovative energy storage solution

The new Mazda6 is coming to our shore early next year, contrary to the optimistic news that we got last year when it was rumoured that the car could be previewed here as early as November 2011. The new Mazda6 is, like the CX-5, is the full-blown product of the Mazda Skyactiv technology, which encompasses the optimized body structure design to weight optimization, redesigned powertrain unit for class-leading power output and emission level as well as the engine start/stop system termed i-Stop. Mazda is bringing the next level of fuel optimization technology to the new 6, called i-ELOOP.

i-ELOOP is Mazda’s innovation on the brake energy regeneration: capturing kinetic energy (the energy generated by a vehicle when it moves) that would otherwise be lost when slowing down. This energy is used to recharge batteries in electric and hybrid cars, for example, or to power the on-board electrical network and save engine power and therefore save fuel. The innovation lies in the energy storing device, a capacitor instead of battery.

A typical vehicle deceleration phase lasts only about 10 seconds.  Realising that the effectiveness of regenerative braking systems to date has been limited by the charging and storage drawbacks of conventional lead-acid starter batteries, Mazda engineers adopted an electric double-layer capacitor (EDLC), which recharges fully in only a few seconds.  An efficient 12V-25V variable voltage alternator generates the electricity and charges the EDLC; a DC/DC converter then steps down the voltage to power electrical components such as the climate control air-conditioning and audio systems, with any surplus going to the starter battery.

A full capacitor charge is enough to run the vehicle’s electrical systems including air-conditioning for a minute or so.  This makes i-ELOOP the perfect companion for i-stop – the latter launched as standard on the Mazda CX-5 and the all-new Mazda6 – as there is no need to revert to battery power even when Mazda’s idle-stop system has shut the car off.  During stop-and-go city driving, charging often resumes before the capacitor is fully discharged.  i-ELOOP can therefore produce most if not all of a vehicle’s electricity needs, whereas normally some of the engine’s output is required just to drive the alternator.  By freeing up this engine capacity, i-ELOOP increases fuel economy under everyday driving conditions.

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