Q: What is a belt-alternator-starter system?

A: A belt-alternator-starter (BAS) system is one type of hybrid vehicle, sometimes called a mild hybrid. In a BAS system, the alternator and starter are combined into one unit. The BAS connects to the engine via a serpentine belt and is mounted like a traditional alternator. The BAS has the ability to crank over the engine, provide additional power during acceleration, and incorporate regenerative braking into the vehicle. In addition to being able to reclaim some previously lost energy through regenerative braking, vehicles with BAS systems can shut down at stops and restart upon acceleration which further increases fuel economy.