The voltage regulator in your motorcycle has the duty of preventing your battery from being overcharged, as well as ensuring that the proper voltage is being supplied to your bike’s other systems. A weak or dead battery is often the first clue that your voltage regulator is faulty, preventing the battery from being recharged while the motor is running. Luckily, testing the voltage regulator is a fairly simple task.
Testing A Voltage Regulator
1. Set your multimeter to 20 volts DC (Direct Current) and connect the positive (+) and negative (-) leads to the corresponding battery terminals. Your battery should be charged, giving you a reading at or just above 12 volts.
2. Start your motorcycle and rev the motor to 5000rpm, maintaining the engine speed during the testing.
3. Using the multimeter, test the battery terminals again. A constant reading of 13.5 to 14.5 volts should be present. This is the proper voltage that will allow the battery to recharge properly.
4. Replace the voltage regulator if the reading is higher or lower than the 13.5 to 14.5 volt range to prevent insufficient or excessive charging. Replacing the rectifier, which converts the alternating current (AC) from your motorcycle‘s stator/alternator to direct current (DC) before recharging the battery, is also recommended at this time.