Vehicle alternator: operation, installation and maintenance

The alternator is one of the most heavily used components in the daily operation of a vehicle. It is essential for powering electrical components and keeping the battery charged. Understanding its role, knowing how to recognise signs of wear, learning how to test it or even replace it yourself can save you a lot of breakdowns. We explain everything you need to know about the alternator, from how it works to how to maintain and replace it.

What is an alternator?

An alternator is a rotating machine that generates alternating current and is an essential component in the operation of a vehicle. Composed of a stator, a rotor, a brush holder or regulator, diodes, and a pulley, it plays a crucial role in converting mechanical energy into electrical energy. This powers the vehicle's electrical system and recharges the battery.

How does an alternator work and how should it be maintained?

The alternator is an essential component in a vehicle. It converts the mechanical energy of the engine into electrical energy to power the various electrical equipment in the vehicle, such as the radio, dashboard, etc., and also to recharge the battery.

In practical terms, the alternator is driven by a belt connected to the engine. When the engine turns, the belt turns the rotor. This is a magnet or electromagnet located inside the stator.

The rotation of the rotor in the stator creates an alternating electric current caused by the phenomenon of electromagnetic induction. This alternating current is then converted into direct current using a rectifier called a diode bridge. A regulator built into the alternator ensures that the voltage sent to the various equipment and components remains constant, i.e. around 14 volts.

The alternator is designed to last for several hundred kilometres, but there are some good practices you can adopt to preserve it further:

Check the tension of the alternator belt, because if it is too loose, it will slip. On the other hand, if it is too tight, it can cause premature wear on the bearings.

Listen for unusual noises such as whistling or squeaking, which may indicate a problem with the bearings or belt.

Keep an eye on the warning lights on your dashboard. If the battery warning light stays on, this may indicate a fault with the alternator.

Avoid electrical overloads by not using too many electrical appliances at the same time, so as not to strain the alternator.

Test the alternator with a multimeter

With a multimeter, you can test the voltage of an alternator with the engine off, with the engine on, and with the engine on and electrical consumers activated. To do this, simply set your multimeter to DC voltmeter mode and connect the multimeter probes to the + and - terminals of the battery.

Engine off: the voltage should be around 12.5 V.

Engine on: the voltage should rise to between 13.8 and 14.5 V.

Engine on with electrical consumers activated: the voltage should remain stable. If it drops below 13 V, the alternator is probably too weak or defective.

Testing at a garage equipped for your vehicle

By taking your vehicle to a garage, you can have a more comprehensive test of the alternator carried out. The voltage will be tested more accurately, as well as the maximum current that the alternator can supply under load.

If your alternator is working properly and shows no signs of wear, you can continue to use your vehicle with peace of mind. However, if the test of your alternator is inconclusive, you will need to consider replacing it.

How to change your vehicle's alternator?

You can change an alternator yourself if you have the necessary equipment and mechanical expertise. Please note that some vehicles may have specific features, so the advice we provide may need to be adapted.

Equipment needed to change an alternator

To change an alternator on a vehicle, you will need:

a ratchet spanner with sockets

a set of flat spanners

a screwdriver

possibly a lever or bar to loosen the belt

a new alternator, which you can find on the Wagendass website using the product reference number.

The tools required may vary depending on the vehicle.

Steps to follow to change an alternator

Once you have the tools you need, you can start changing the alternator.

Disconnect the battery, starting with the negative terminal to avoid a short circuit.

Locate the alternator, which is usually located at the front of the engine, connected to the belt and secured by two or three bolts.

Loosen or remove the belt, using the appropriate method for the type of tensioner.

Disconnect the connections.

Unscrew the alternator mounting bolts.

Install the new alternator, retighten the bolts, reconnect the connections and replace the belt.

Tighten the belt.

Reconnect the battery and test it: check that the belt is turning quietly, that the battery light is off and that the charging voltage is correct

It is important to always consult the vehicle manual for specific details such as location, belt type and tightening torque.

If access is difficult, it may be necessary to remove surrounding components. Finally, be careful not to touch the battery terminals with a metal tool while replacing the alternator.

Whether you simply want to test your alternator or replace it, it is essential to choose a suitable and reliable part. Discover the selection of alternators offered by Wagendass that are compatible with your vehicle to quickly find the model you need.