Why do FCEVs have a battery?

Have you ever wondered why fuel cell electric vehicles (FCEVs) have a battery? Of course, regular gasoline cars and diesel trucks have batteries too. The battery in the hydrogen fuel cell truck fulfills many of the same functions as those batteries, like providing the power to start the vehicle and for short-term use of functions like headlights, radio, windshield wipers, or alarm system when the engine is off. But there is another key use. Like regular automobiles, FCEVs are optimized to produce power from the fuel cell system at an ideal rate, creating the best fuel efficiency. Due to this, the fuel cell system alone is not set up to respond immediately to increases and decreases in power requirements. This is where having a battery comes in.