Dynamo (DC Generator)

A dynamo is an electrical generator driven by the engine. Unlike an alternator, it uses a commutator and brushes to deliver direct current (DC). It is often confused with the alternator, which produces alternating current.

Dynamos were used on classic British and German motorcycles and older mopeds, often with a mechanical voltage regulator. They are heavy, produce little power at low revs and need brush maintenance. From the 1960s and 70s, AC alternators with rectifiers took over on most bikes.

On a classic bike, low charging output is often caused by worn brushes, a dirty commutator or a faulty regulator. Many restorers convert to a modern electronic regulator or an alternator kit for reliability.