In the battle for fuel economy, every little bit helps. By either diverting or capturing energy during optimal times, Hyundai saves some gasoline with its Smart Alternator Control.


Alternators, which run off the engine, produce the power needed to operate the car’s electrical systems and charge the battery.


This new approach uses a battery sensor, the engine’s control unit and a variable output alternator to match the system to the driving conditions. The alternator’s output voltage is lowered during acceleration, allowing engine energy to be used more efficiently to move the car, and raised during deceleration to charge the battery with the help of the vehicle’s motion.


“It’s a concept that was learned from hybrid vehicles,” says Tim White, senior manager of the powertrain department at the Hyundai-Kia American Technical Center in Michigan.


“When you’re accelerating, you want all the power you’re using to accelerate the vehicle. You don’t want to waste any energy charging the battery at that point.

“When you’re slowing down, you have all this kinetic energy from the inertia of the vehicle rolling, and you can use it to charge the battery. In a hybrid, it’s called regenerative braking. We’re using the concept, but in a much smaller scale. We use the energy that would otherwise be wasted to increase the charging rate of the battery.”

Like many automakers, Hyundai uses a system that temporarily shuts off the fuel supply during deceleration when conditions are right. As the vehicle’s wheels turn, the engine’s crankshaft continues to spin, which keeps the alternator turning and charging the battery even though no gasoline is being consumed. White estimates that the combined systems save a minimum of about one to two percent in fuel economy.

The Smart Alternator Control doesn’t affect battery life, White says. “If anything, it’s neutral to sometimes favourable. In the past, the system wasn’t smart; it just tried to maintain the voltage. Now, it can ‘see’ in detail what the state of charge of the battery is. If the battery was really discharged, the sensor would communicate that to the engine computer, and it would charge the battery even during acceleration. It would say something’s not right, so we can’t use this fuel economy logic at this point in time.

“It’s also a relatively low-cost fuel economy item.” The changes are pretty minor in the alternator.”

Used on the all-new Sonata and Tucson, the system will eventually be rolled out across all of the company’s vehicles as new models are introduced.