Brush type generator ends are a great option for someone looking for a low cost and compact generator end. Because brush type generators have a commutator ring and brushes, this type of generator requires maintenance. Brush generator replacement parts are typically less expensive than exciter type or brushless generators. On average, brush generator ends feature about 75%-80% efficiency. This is less superior to the exciter or brushless generator, which is typically featuring about 85%-95% efficiency. This difference in efficiency means that more of the total power of the engine is being converted into rotational force rather than being lost as heat.