How Regenerative Braking Works

Whenever we slow down, most often than not, we use the car’s brakes? Well, did you know that whenever we brake, we effectively waste energy in the process? Neither did I, actually, and here is why we are actually wasting precious energy whenever we use the brakes.

Our car’s engine produces the power that propels our car forward, and that, of course, uses energy, and whenever we lift off the gas pedal, the car can continue to keep moving forward, because it still has what we call, kinetic energy. When we use the brakes, the kinetic energy is converted into heat through the friction between the brake pads and the brake discs. If we try remembering our high school physics, heat is a form of energy, and the law of conservation of energy states that energy cannot be created nor destroyed, which brings me to the question, where does all the heat go? This is where regenerative brakes gain its purpose.

Energy Flow Monitor In A Toyota Highlander Hybrid In Electric-Only Mode

Regenerative brakes are designed to use or convert all the wasted heat energy into something much more useful, like electricity, but how is this converted into electricity? First, let’s talk about what powers our car’s electronics. The alternator.

Conventional alternators are always on, constantly charging our car’s battery in order to supply electrical energy to the vehicle’s electronics, which also means constantly sapping power from the car’s engine. In a car with regenerative brakes, the car’s alternator switches on only when you lift your foot off the gas pedal, charging the car’s battery through the spinning of the wheels from the car’s momentum, or whenever you step on the brake pedal, and the heat produced in the brakes feed the alternator, charging the car’s battery. The alternator turns off whenever you step on the gas pedal, with the duty of sending electricity to power the electrical systems left solely to the batteries, which means that the alternator only saps power from the engine whenever we brake or coast.

Energy Flow Monitor In A Toyota Prius When Braking

All hybrids and EVs have regenerative brakes as standard since keeping the batteries charged in these types of vehicles is essential in order provide the proper propulsion for these types of vehicles. For non-hybrids, regenerative brakes are used to power the car’s electronics, having been equipped as standard on all BMWs for nearly a decade since the launch of their BMW EfficientDynamics program. While the system may sound perfect, there is a more innovative way in storing this energy, for non-hybrids at least, all thanks to the intelligent folks from Mazda.

Typical regenerative braking systems charge a battery, but the problem is, batteries can’t be charged and discharged in quick successions, a clear observation we see whenever we charge our gadgets. This is where Mazda’s i-ELOOP system comes in to save the day. In Mazda’s i-ELOOP system, instead of charging the car’s batteries, the regenerative brakes charge what Mazda calls an EDLC, or an Electric Double Layer Capacitor. A capacitor is like a battery, but it can be charged fully and be discharged completely in a matter of seconds. This doesn’t mean that Mazdas do not have batteries. Instead, the capacitor acts as sort of like an assistant to the car’s battery. The capacitor supplies power to the car’s electronics whenever you step on the gas pedal, while the battery supplies power to the car’s electronics whenever you release the gas pedal, in which at the same time, the alternator charges the capacitor. Through this system, Mazda claims that it doesn’t just reduce the load from the car’s engine, it also reduces the load from the car’s battery, making it last longer than usual.

What are the advantages of these systems you may ask? Well, first is performance. These systems limit the alternator from sapping energy from the car’s engine, meaning that 100% of the engine’s power goes through where it should be going through in the first place, the car’s wheels. This also improves engine response, making your car even more fun to drive. Another inherent advantage is fuel economy. Since the engine is free from providing power to the car’s alternator whenever we need more power while driving, the engine is doing a lot less work than usual. Real world testing has proven that regenerative braking systems have improved a car’s fuel consumption by as much as 3-10%, and this is simply through an intelligent solution that recycles a car’s wasted heat energy whenever we use the brakes.

These are the cars on sale in the Philippines equipped with regenerative braking.

The Entire BMW Line-Up

Mazda 3 (2.0 R Variant) – P1,195,000 – P1,198,000 (Add P16,000 for Soul Red Paint)

Mazda 6 – P1,745,000 (Add P16,000 for Soul Red Paint)

Honda CR-Z – P1,390,000 – P1,950,000 (Add P20,000 for Pearl Paint Finish)

The entire Lexus hybrid line-up (ES Hybrid and IS Hybrid Not On Sale In The Philippines)

Of course, no one will forget the car that made the hybrid popular in the first place. The Toyota Prius (P2,250,000 +P15,000 for White Pearl), and its newer, smaller derivative, the Prius C (P1,475,000 + P15,000 for White Pearl).