What is the difference between an Alternator and a Dynamo as far as working, efficiency and performance is considered? Which is better and why?
A21: Any Rotating Electrical Machine is ‘inherently’ AC! For DC applications, as necessitated in a Car due to the unavoidable existence of a Battery, which can only be DC, the Dynamos/Alternators/Starters all ‘have’ to be ‘converted’ to be ‘DC Friendly’. In the Dynamos and Starters, it’s done by using an in-built ‘Rotating Mechanical Rectifier’, commonly known as the ‘Commutator’. On the other hand in an Alternator, it’s done by using a built-in solid state ‘Bridge-Rectifier’ system. Talking of a Yesterday’s Dynamo, which was invented long before reliable and durable ‘solid-state/high-powered’ Rectifiers became commercially viable, the commutator part of it was the ‘black-sheep’, by way of reliability/durability and Radio-interference. Besides, it needed an external ‘cut-out/voltage-regulator’ too, coz of its inability to develop sufficient voltage at idling Rpms and in any case when the Engine was to be shut down, it had to be isolated from the Battery as otherwise, the Battery would