How can a Bosch 90 Amp alternator take the place of a 120 Amp alternator?
The Bosch 90 amp is a “hot” rating. This means that when you run your vehicle and the alternator becomes hot, the output is still 90 amps (if needed). American alternators utilize a ‘cold’ rating. However, when a vehicle runs it becomes very hot and the alternator is less efficient when its hot. Therefore, the actual output of the alternator is 70% to 80% of its “cold” rating. Remember that an alternator’s output doesn’t necessarily correlate to a vehicle’s amperage needs. It depends on the accessories and the amount of amperage they collectively draw.
