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Mazda announces world first capacitor-based regenerative braking system


November 24, 2011

Mazda claims its new i-ELOOP system is the first passenger vehicle regenerative braking system to use a capacitor instead of a battery

Mazda claims its new i-ELOOP system is the first passenger vehicle regenerative braking system to use a capacitor instead of a battery

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While Toyota took out the Tokachi 24-Hour Race in 2007 with a Supra HV-R hybrid race car featuring a quick-charging supercapacitor-based regenerative braking system, battery storage has so far been the norm for these systems in production vehicles. Now Mazda is charging things up with its new "i-ELOOP" system intended for internal combustion engine-powered vehicles. The i-ELOOP is billed as the world's first passenger vehicle regenerative braking system that uses a capacitor in place of rechargeable batteries to temporarily store energy captured from braking.

Regenerative braking systems used in most current hybrid and electric vehicles convert a vehicle's kinetic energy as it decelerates into electricity, which is used to recharge a battery that powers an electric motor. In contrast, Mazda's new "i-ELOOP" (Intelligent Energy Loop) system is designed to be used in internal combustion engine-powered cars with the energy captured used to power the climate control, audio system and other electrical components. This gives the system the advantage of not requiring a dedicated electric motor or battery.

Mazda claims the i-ELOOP system improves the fuel economy of a vehicle by around 10 percent under real-world driving conditions with frequent acceleration and braking.

i-ELOOP uses a new 12-25 V variable voltage alternator that generates electricity at up to 25 V before sending it to a low-resistance Electric Double Layer Capacitor (EDLC) for storage. Because capacitors can be charged and discharged much more quickly than batteries, the capacitor used in the i-ELOOP system can be fully charged in seconds. A DC/DC converter then steps down the electricity from 25 V to 12 V before distributing it directly to the vehicle's electrical components.

The system is also used to charge the vehicle's battery when necessary and works in conjunction with Mazda's i-stop idling technology to extend the period that the engine can be shut off.

The new i-ELOOP system, along with its range of SKYACTIV technologies, fits in with Mazda's focus on improving the efficiency of internal combustion engine vehicles rather than developing hybrid electric vehicle technology of its own, having opted instead to license technology used in the Toyota Prius for any near-future hybrid vehicles. Mazda says the i-ELOOP system will start to appear in its vehicles in 2012.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

very good start. this opens up a greater speed range at which energy can be regenerated without affecting the battery. even the lag time in acceleration that arises from engine shut-off is reduced. all this can be done while improving overall efficiency. bravo mazda!


Ah! Finally! Someone has come out with hybrid\'s retarded cousin! All the extra expense and most of the extra complexity without the benefit. Way to go!

Bryan Paschke

\"Ah! Finally! Someone has come out with hybrid\'s retarded cousin!\"

Maybe you could read the article before ranting.

Captain Obvious

\"This gives the system the advantage of not requiring a dedicated electric motor or battery\" in paragraph 2, followed by: \"The system is also used to charge the vehicle\'s battery when necessary\" in paragraph 5. So why is it charging a battery that is not required? Or is it just not \"DEDICATED\" ? Dedicated to the one you love? Dedicated to what? Are some electric motors more dedicated than others? Please explaine what the heck you are talking about. Could you compare this to how \"dedicated\" the motor is in a GM Buick Regal mild hybrid?


There are several drag racing electric vehicles that use ultra-capacitors already.

Note: The FAA has speed restrictions on commercial airliners below 10,000 ft (about 250 knots, . . . about 288 mph) !!!


I agree this is stupid. None of the recovered energy is used to make the car move. It\'s easy to see why they use capacitors, the amount of energy needed to run the car\'s electrical system is paltry compared to actually moving the vehicle. This system will have minimal impact on mileage, probably just enough to offset the added weight of the system.


Those of you poo-pooing the technology have to realize that batteries are inefficient. And alternators are a huge drag non engines. I read a while back that changing out the car battery with a capacitor greatly enhances MPG. How much? Can\'t remember. But by using the energy from breaking to run the rear defrost and other high energy options, through a capacitor, you get rid of the inefficiency of a battery, while greatly reducing the load on the engine from the alternator. Granted it complicates things. But what is the failure rate of capacitors? They last just about forever. As for the control system.....that may be another story.....


Cap, mpg increases on the order of 10%? For this I\'m adding the expense of another system? And that increase is assuming city driving and full use of the comfort systems in the car? I like my comfort as much as the next person, but I\'m not excited about adding cost and complexity for minimal gain.

Use the capacitors to reduce the time needed to charge an electric car or recover more energy during braking for an electric car and I\'ll be impressed. But this article is about a car that simply gets it wrong. I can improve my mpg more than what they\'re talking about simply by altering my acceleration and braking habits.

Bryan Paschke
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