How To Test an Alternator

Test the Resting Battery Voltage

• If you don’t already own one, get a cheap multimeter.
• Set it to read volts.
• With the engine off, touch the red probe to the battery’s positive terminal and the black probe to the negative terminal.
• The voltage should read between 12.3 and 12.8 volts. If it’s below that, charge the battery with a battery charger before you conduct the test again.