Testing an alternator

How to check if the alternator give off a charge


Connect a voltmeter in parallel between the negative terminal of the battery or on the body(ground) and the (B+) wire on the alternator this should give a reading of the voltage that is produced

What checks to do before testing

• visually inspect the wiring for any loose connections or corrosion
• check the tension of the belt that drives the alternator and its condition (should not have cracks)
• check to see that the charging light comes on when the car is switched on
• check the alternator bracket 
• visually inspect the alternator its self for any obvious damage or if any oil has leaked on to it

Testing the voltage drop

Before testing start the engine

To test the voltage drop connect the multimeter with the com wire to the negative terminal of the battery and the positive wire to the body of the alternator. To check the positive voltage drop connect the com wire to positeve terminal on the battery and the positive wire to the B+ terminal.