A dual-voltage alternator is a single alternator which produces two simultaneous and independently regulated electrical outputs, as shown in Fig. 1. This means that a vehicle with a single dual voltage alternator will be capable of powering, simultaneously, both the standard vehicle 12 volt electrical system (which powers lights, horn, instruments) and also to power another electrical system at a different voltage. The other, or secondary electrical system, is typically a higher voltage system. It may be a 24 volt electrical system to power military communications equipment, or it may be a 48 volt electrical system to provide power for other vehicle electrical power needs, such as electrical heaters for engine emission control. This paper describes a dual-voltage alternator design for automotive applications.