The charging system in your Mazda RX8 includes the alternator. After the engine is started, the alternator recharges the battery and provides electrical power to the rest of the vehicle's electrical system. You can test the alternator to verify that it is supplying the correct power output by using common electrical test equipment and procedures. The average home mechanic will complete this task in just a few minutes.
Turn the ignition key to the "off" position and test the battery's voltage. Set the meter to read volts, then touch the meter's leads to the battery terminals. Charge the battery if the voltage is below 12.5 volts before testing the alternator. A partially discharged battery might cause the alternator to malfunction.
Start the engine and turn off all electrical accessories such as the radio and air conditioning. Touch the meter leads to the battery and observe the voltage displayed on the meter. The correct voltage should be around 13.5 volts. If the voltage is the same as the battery voltage with the engine off, replace the alternator.
Turn on the air condition, blower motor, high beam headlights and radio. If the voltage drops to battery voltage, replace the alternator.
