How to tell you have a faulty alternator

When your car alternator stops functioning, without a doubt your anxiety levels will shoot up. Why? Your car won't move an inch.

And the frustration that comes with an immobile car when you have a thousand and one things to do is almost palpable.

 The car alternator is supposed to recharge your car battery as the car diminishes the electrical power of the battery. It powers the lights, air conditioning and charges the battery. How do you tell it is faulty before it surprises you?

Removing cable from terminal

One of the common ways of testing the effectiveness of the alternator is popping the bonnet open, starting the car and while it's running, removing the cable from the negative terminal of the battery, if the car goes off, the alternator is not generating enough electricity.   

Alex Tugume, a mechanic with Benghazi Auto Garage, Ntinda says besides that, also the warning light stays on once the car is started to indicate the battery is not charging.

“To test if the alternator works, you remove the terminal. If the car continues running, it is okay. But if it goes off it is dead. Also, it has a warning light, so when you start the car and the battery light stays on, it is not charging. The alternator can be repaired, could be the capacitor or diode that is dead, or you can buy a new one,” explains Tugume.

James Mugaga of Raquel Motors says once the car is started, it brings the light and goes off, the battery is not charging.  

The headlight test

Here you start the car, with it in park (P), step on the accelerator and have another person observe the headlight, should it dim or flicker the alternator is dead, should it maintain its brightness, the alternator is in good condition.

The screwdriver

The goal here is to see if it produces a magnetic field. Pop the bonnet open, start the car, get a screwdriver that is clean and free of rust, wear a glove for insulation and place it near the rotating part of the alternator and if there is no magnetic pull, then your alternator is faulty. The advantage here is you do not need a voltmeter to be sure.  

Rev the engine

With your car radio on, rev the engine, if it starts heckling whenever you hit the accelerator pedal, start suspecting the alternator. It is a sign the alternator diodes are leaking energy to areas they are not needed.

Have it tested

Get your alternator tested by a professional mechanic where they will take it out and test it. It will have to range between 12 and 13.5volts. If it falls below this, it is most likely defective while if it shoots above, it means the battery is overcharging. Mugaga says fixing a broken alternator is possible, but the ideal is to replace with a new one. “Replacing is better than having the old one fixed. The difference between the two alternatives might be sh100,000,” he notes.