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Mazda to begin deployment of i-ELOOP ultracapacitor-based regenerative braking system for passenger vehicles in 2012

Mazda’s ‘i-ELOOP’ regenerative braking system. Click to enlarge.

Mazda Motor Corporation has developed the first production passenger vehicle regenerative braking system that uses an ultracapacitor. The system, which Mazda calls ‘i-ELOOP’, will begin to appear in Mazda’s vehicles in 2012. In real-world driving conditions with frequent acceleration and braking, i-ELOOP improves fuel economy in stop-and-go driving conditions by approximately 10%, according to the company.

Compared to batteries, ultracapacitors can be charged and discharged rapidly and feature a very long cycle life. i-ELOOP 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.

The i-ELOOP system features a new 12-25V variable voltage alternator; a low-resistance electric double layer capacitor (EDLC) and a DC/DC converter. i-ELOOP starts to recover kinetic energy the moment the driver lifts off the accelerator pedal and the vehicle begins to decelerate. The variable voltage alternator generates electricity at up to 25V for maximum efficiency before sending it to the Electric Double Layer Capacitor (EDLC) for storage.

The ultracapacitor, which has been specially developed for use in a vehicle, can be fully charged in seconds. The DC/DC converter steps down the electricity from 25V to 12V before it is distributed directly to the vehicle’s electrical components. The system also charges the vehicle battery as necessary.

The name ‘i-ELOOP’ is an adaptation of “Intelligent Energy Loop” and represents Mazda’s intention to efficiently cycle energy in an intelligent way. ‘i-ELOOP’ also works in conjunction with Mazda’s ‘i-stop’ idling stop technology to extend the period that the engine can be shut off.



It's great to see more EV traction improvements in production and generating revenue/+profits? - the real test.


Are we to assume the standard belt driven alternator is replaced with the variable voltage unit? If the ICE continues to turn the regulator how much energy is conserved??

william g irwin

Just for grins outside the box, the alternator has to run at engine speeds - 700 to 7000 rpm. One aim is to shut off the engine while stopped/decelerate to save fuel. Why not run the alternator after the tranny and gather the energy w/o running the engine while decelerating - spend less energy on dragging the engine, gather more energy from deceleration, run the alternator on a narrower range of speeds! Just a thought!

Henry Gibson

Modern flywheels have been shown to give good service instead of capacitors in F1 race vehicles. ..HG..


a nice alternative is GM's eAssist or BAS + system.. but with much lower cost from mass production and simplification.. the premium for the eAssist equipment is about $3000, for contrast the hybrid premium for the Prius is about $1500 (might be a bit more with the Yen shenanigans). GM needs to put a bit more work on it and make it standard across the line.

The system Mazda is proposing is simply a smart alternator, with a tough battery... they should just go ahead and run the whole car on 24v.

william g irwin

I sense a lot of resistance in the past to changing our intrenched 12v systems considering the whole parts industry. Why not take it to 36v or more? Seems like weight savings and efficiency advantages galore. But EVs and PHEVs etc. went way beyond that w/voltage converters etc. And these converters are getting fairly common and less expensive too.
Seems like 36v or so would be safer for the back yard and pro repair folks. Just a little energy for the efficiency boosters and supplementals, and a whole lot more energy for primary drive.

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