Alternator regulator Piaggio OEM Aprilia RS4 125 up to year 17 (type: TW), RS 125 from year 18 (type: KC), SX 125 from year 18

To charge the battery and to supply the board net a voltage of 12V-14V is needed from the alternator. With increasing engine speed the voltage of the alternator also increases. If this happens again and again, one can safely assume a defective regulator. However, before each exchange with a multimeter the function of the component should be confirmed.