[Crankster]

The battery is really only to start the engine technically speaking, the current for the lights, ignition, and accessories is provided by the generator or alternator.

The battery does act as a "flywheel" of sorts, smoothing out spikes or sags from the pulsed DC output. It is true that a generator charging system employs a cutout in the regulator to prevent the battery from backfeeding into the generator windings at low RPM or at shutdown. In low RPM situations where the cutout is open, the battery does carry the entire vehicle electrical load. Alternators employ a diode pack and work much better at low RPM. (And high RPM for that matter)