An Automotive Alternator is a key component in a modern engine system. The alternator is use to create electrical power for the system and charging the engine battery. Without a working generator, most engines will not run properly. They may be able to run a short time utilizing power from a battery, but usually this power will drain quickly and immobilize the vehicle. A failing alternator should be replaced as soon as possible to avoid battery drain or damage, and avoid a stalled vehicle.