In our article today, we shall be focusing on how to test car alternator, before I show your this, will like to see the work of an alternator in a car, we shall also look at signs of a bad alternator.
What Does Alternator Do In A Car?
While the battery is necessary for starting your automobile after it is turned off, the alternator keeps your car running. While driving or idle, the alternator powers most of your car’s electronic components, including your headlights, electric steering, power windows, windshield wipers, heated seats, dashboard instruments, and radio. The alternator provides direct current (DC) electricity to all of them. Your alternator is also in charge of charging your automobile battery while you’re on the road.
Mechanical energy is converted into electrical energy by the alternator. When your engine is turned on, it drives a drive belt that is coupled to an alternator pulley. The alternator’s rotor shaft is rotated by the pulley, which rotates a series of magnets around a coil. The alternating current (AC) generated by these spinning magnets is then directed to the rectifier of the alternator. The rectifier converts AC power to DC electricity, allowing your car’s electrical systems to operate.
Alternators are designed to last the life of your car, but this isn’t always the case. General wear and tear, heat damage, abuse, water exposure, faulty parts, and frayed wires can all cause your alternator to fail before your automobile is scrapped.
Read also: What Are The Signs Of a Bad Alternator?
Signs Of A Bad Alternator
If your experience any of these signs while driving your car, you should know that your alternator has developed some fault and needs urgent attention.
Dim Or Very Bright Light
When an alternator starts to fail, the voltage to your electronic equipment becomes erratic. Under- or over-performing equipment, such as headlights that are either too dim or excessively brilliant, is a common example. You can also notice flickering lights or lights that go from bright to faint and back again.
Dead Battery
A dead battery, on the other hand, could indicate a problem with your alternator. While the engine is running, a defective alternator will not adequately charge the battery, causing the charge to decrease faster than usual. Jumpstarting the car is one approach to see if the problem is with the battery or the alternator. If you jumpstart your automobile and it continues to run, your battery may need to be replaced. If you jumpstart your car and it dies soon after, it’s possible that your alternator isn’t supplying enough power to the battery.
Trouble Starting Engine
Trouble starting your engine could indicate that your alternator is failing to charge the battery, as previously stated. So instead of hearing the purr of your engine when you turn the key in the ignition, you hear a worrying clicking sound.
If your car stalls regularly while driving, though, it could be a sign that the spark plugs and coils aren’t getting enough electricity from the alternator to keep the engine going.
These are some of the common signs that shows your alternator has problem. There could also be other signs like, growling or whining noise, smell of burning rubbers, battery warning light on dashboard etc.
Read also: How To Avoid Overheating in Cars
Let’s now consider how to test an alternator.
How To Test Car Alternator
To test car alternator, you will need a multi-meter and with the engine on, do the following:
Step 1
Open your hood to get a great view of your car’s battery. Locate your alternator and double-check that the alternator belt isn’t slipping.
Step 2
Set your multimeter to a voltage of 20 volts
Step 3
Turn on the engine. Check that the alternator pulley / belt is spinning freely without slipping at this point.
Step 4
The voltage emanating from the alternator can be tested in two ways. Place the positive multi-meter probe (red) on the red terminal connector coming out of the alternator if you have easy access to it without having your body parts / clothing / etc tangled in the spinning pulleys. Take the negative (black) multi-meter probe and place it against a metal component of your vehicle’s structure (like a bolt head nearby or even the negative terminal on the car battery).
Do not connect the alternator to the ground. That might be problematic. On your multi-meter display, you should now see a reading. If you don’t have easy access to your alternator, you can test it by touching the positive multi-meter probe to your battery’s positive terminal and the negative probe to the negative terminal.
If the alternator is in good functioning order, your multimeter should register around 14 volts (typically 13.8-14.2). It’s conceivable that the voltage regulator on your alternator is malfunctioning or failing if it’s reading more than 14 volts (more than 15 volts). If it’s reporting less than 13-14 volts, there are a few things that could be causing it.
To begin with, it’s likely that your engine’s idle speed is too low for the alternator to produce enough voltage/power. Take a reading after revving the engine to 2000 RPM or higher. If the voltage is still too low, make sure your alternator’s connectors are secure and the alternator belt is not slipping and rotating appropriately on the pulley. If the alternator is still not producing enough power, the voltage regulator or the alternator itself may need to be replaced.
To efficiently charge a 12 volt car battery, a car alternator must produce at least 13-14 volts (preferably between 13.8 and 14.2 volts). If the alternator is producing too much electricity (15+ volts), the battery acid is likely to boil over and leak out. When a battery is nearly fully charged, the alternator will no longer be able to charge it, and the reading you get from the battery probing method will just be the voltage coming from the battery. In this scenario, simply leave your lights on while driving for ten or fifteen minutes to somewhat drain your battery.
It’s also a good idea to test the battery terminals with the motor off, then switch it on and test the terminals again. With the car turned off, your battery should register around 12-13 volts if it’s about fully charged. If you’ve driven your car for a long time and the voltage reading is in the 13-14 volt range when driving, but then you turn it off and the battery voltage decreases to much below 12 volts (10 volts or below in freezing weather conditions), your battery is likely in need of maintenance or replacement.
With this tutorial, you should be able to test your car alternator and know whether it’s functioning properly or not.
