What are the most common problems with an alternator and how do you solve them?

An essential component in your vehicle: an alternator. To avoid vehicle charging problems and to convert mechanical energy into electrical direct current, a properly functioning alternator is indispensable. What should you pay attention to when buying an alternator? How do you recognize possible damage or problems? And what are the solutions?

How does an alternator work?

Een dynamo heeft twee functies: het opladen van een batterij om het elektrische systeem van een voertuig van An alternator has two functions: charging a battery to power a vehicle's electrical system when the engine is running. In addition, the alternator is part of your vehicle's charging system that produces electricity for many appliances.

The alternator is mounted on the engine and is connected to the crankshaft (which is inside the engine) with a v-belt or multi-ribbon. It ensures that electrical energy goes to the battery. You should think of the battery as a battery. The alternator supplies the required energy and the battery/battery is on standby.

It can be compared to a dynamo on a bicycle: when you pedal and the tyre turns, the dynamo turns and the light comes on. This also applies to other vehicles; when the engine turns, it supplies power. Of course, the dynamo in a vehicle is a bit more complicated, but in basic terms it works the same. Thereby, a vehicle alternator also ensures that the vehicle's battery stays charged.

How do you know if an alternator is broken?

You can recognize a non-working alternator by a lit battery lamp in your vehicle. It is also possible that the lights of the safety systems come on. Think ABS or your airbag system. Then there is a good chance that the engine will fail. You may also hear unusual noises under the bonnet when starting.

Below are the five most common symptoms of a bad or failing alternator:

1. Indicator light 

A first sign of problems with the charging system is the "battery", "ALT" or "CHARGE" warning light that comes on in the instrument panel while driving. This means that the alternator has stopped providing electric voltage/current and your vehicle is running on battery power. If the light comes on only intermittently, it usually indicates worn or bad carbon brushes in the alternator. However, burning the light does not always mean a damaged component. The light is also sometimes triggered by a sensor giving the wrong message.  

2. The engine starts slowly or not at all

If the battery has too little charge, the engine starts slowly or not at all.

3. Battery overheats

An overcharged battery causes overheating. If that problem is not addressed in time, it may ruin the battery. Another possible sign that the battery is overcharged is when the battery terminals continue to show corrosion/rust. So bad connections between alternator and battery or a bad ground connection.

4. Noises under the bonnet

Squeaking, buzzing or grinding noises coming from the engine are often caused by bad alternator components, a loose or worn v-belt or multi-belt or a faulty belt tensioner. Bad alternator bearings, rectifiers, rotor shaft, stator winding, slip rings, brushes and other parts in the alternator with mechanical or electrical problems then often make noise.

5. Dip lights

Do the headlights, instrument panel or interior lights dim? Then the battery probably has too low a charge or there are one or more faulty diodes in the alternator.

Should the alternator no longer supply power, this can have several consequences:

1. The v-belt or multi-belt is too slack or broken. In this case, you can easily have it repaired at a dealer or specialised company.
2. The alternator itself is broken. This alternator can easily be replaced. 

To measure is to know

To test whether an alternator is charging the battery properly yourself, you need a voltmeter. Connect this to the battery terminals. It is useful to measure this first when the engine is off. All other power-consuming systems, such as the radio and lights, are switched off. Then turn on the engine and compare the number of volts on the voltmeter with your previous test. As the battery runs down, it goes below 12.2 volts. This battery voltage is too low to start an engine with. A properly working alternator is between 13 and 14.8 volts. 

To avoid problems with your alternator, you should also regularly check the timing belt for tension and dryness cracks. Check this by pressing on it with your finger. When doing this, the belt should be compressed to a maximum of one centimetre, otherwise the belt is too slack and worn out.

The service life of a multibelt depends on the load. If you don't use the air conditioner much, the timing belt is under less load and will last longer.

The table below lists various alternator problems and solutions:

Problem	Possible cause	Solutions
Warning light does NOT illuminate (with ignition on and engine off)	Blown fuse	Check fuses LOADING, IGN, ANG MOTOR; replace them if necessary after you fix the cause.
	Burnt-out bulb	Replace bulb
	Wiring connections loose	Check voltage loss in circuit, tighten loose connections
	Faulty relay	Check relay, if used, for continuity and proper operation
	Faulty controller	Check alternator
Warning light does not go off with engine running; battery overcharged or undercharged	Loose or worn drive belt	Check drive belt; adjust or replace if necessary after fixing cause.
	Defective battery or battery connections	Check battery and connections
	Blown fuse or fusible link	Check fuse and fusible link; replace if necessary
	Faulty relay, regulator, or alternator	Check charging system performance and operation of components
	Defective wiring	Check voltage drop
Noise	Loose or worn drive belt	Check drive belt; adjust or replace if necessary
	Worn alternator bearings	Replace alternator
	Faulty diode	Replace alternator

Do you have any questions?

Do you have questions about alternators or would you like more information on which alternator is most suitable? Then please contact one of our product specialists, find a Kramp dealer near you or contact us at knowledgecenter@kramp.com. Curious about all the starters and other engine parts we sell? Then take a look in our webshop.