When the supercapacitor is discharged, but the electrical load is at 50 A and below, and the car is being driven in cruise or on an upgrade, no regenerative braking energy is available. The alternator then will charge but through the dc-dc converter. The smart charging system may compensate for transmission losses in this type of operation by running the alternator at higher voltage with reduced current, a more efficient approach. An example cited by Mazda: the charging system is more efficient at 25 V/ 25 A than 12.5 V/ 50 A. The smart system is always looking for the "sweet spot," Mazda spokesman David Coleman explained, and that also improves battery durability.