Wondering if your alternator is still working properly? It can be difficult to determine if your alternator is still good if you don't know what to look for. You can test your alternator well with a voltmeter. If you have some experience with cars, there are some other methods you can try. Read on to learn how to check if your alternator is working properly.
Steps
Method 1 of 2: Using a strain gauge
Step 1. Buy a strain gauge
You can already buy a voltage meter for less than 20 euros, at a car parts store or hardware store. You really don't need an expensive one, a cheap version is good enough to measure a dynamo.
You can also use a multimeter. A multimeter measures the voltage, but also the current and resistance. To check your alternator you need to measure the voltage
Step 2. Check the battery
The battery starts the alternator and the alternator in turn ensures that the battery is charged. If your battery is (almost) empty, the dynamo cannot start, and then you have nothing to test with a voltage meter. If it is cold or if you have an old battery then the problem may be with the battery and there is nothing wrong with the alternator. That is why you should always test your battery before testing the alternator. You do that as follows:
- Turn off the engine. Before connecting the voltmeter, the motor must be off.
- Open the hood.
- Connect the voltage meter to the battery. Hold the red end of the voltmeter against the red terminal of the battery and the black end against the black battery terminal. Do not touch the battery with your bare hands.
- Read the voltage meter. If the meter shows more than 12.2 volts, the battery is full enough to get the alternator going, so in that case you can now start testing the alternator.
- If the meter reads less, you must first charge the battery and test again or use another method to test the alternator.
Step 3. Start the car and accelerate to 2000 rpm
This activates the voltage regulator that puts the alternator in high gear.
Step 4. Run the engine and test the battery again with the voltmeter
If you now read the voltage meter, the voltage should be at least 13 volts. If the voltage goes back and forth between 13 and 14.5 volts by accelerating the alternator is in good condition. If the voltage stays the same or if it decreases, your alternator is not working properly.
Repeat the procedure with the lights, radio and air conditioning on. The alternator will charge when the voltage meter is above 13 volts with the engine at 2000 RPM and all appliances turned on
Method 2 of 2: Keeping an eye on your alternator
Step 1. Check the alternator gauge on your dashboard
If you have a gauge on your dash that reads volts or amps, it's the dynamometer. Turn on the blower with air conditioning or heating, your headlights and any other accessories that require power from your dynamo. See if that makes the pointer go down. If the meter shows more with a running engine than with a hot engine, you can assume that the alternator is charging the battery properly.
Step 2. Listen to the alternator while the engine is running
If there is a problem with the bearings, you may hear a squeaking noise, which becomes louder when many electrical accessories are simultaneously drawing power.
Step 3. Turn on the radio and accelerate
If the radio starts to sound weird when you accelerate, there is probably something wrong with your alternator.
Step 4. Find a place where you can have your alternator tested for free
Many businesses are happy to sell you a new alternator, so they will also be happy to test your old alternator for free. Remove your alternator from the car and take it to a shop or garage for testing.
Tips
- Even if the conclusion is that the alternator is not working, the problem may lie elsewhere. Maybe the fuse has blown, maybe it's a relay or a broken voltage regulator.
- If it's really cold outside, it's a good idea to turn on your headlights for a minute or two before starting the car. A warm battery will start a cold car more easily.
Warnings
- Watch out for your hands, loose clothing and jewelry when you're working under the hood with the engine running.
- Some people recommend testing the alternator by starting the car, disconnecting the negative battery terminal, and then waiting to see if the car turns off or not. Do not try this method; your voltage regulator, alternator and/or electrical components may burn out.