The battery charging light was on: what should I do?

If the battery charging light comes on , the driver begins to worry. And the reason for this is serious - the capacity of the battery is unlikely to be enough to overcome a significant run. And the reason that the lamp caught fire can be the failure of the generator, battery, malfunction in the on-board network. All these factors should be considered more carefully, so that in the event of an unforeseen situation, it is quickly eliminated. To monitor the presence of charging on the battery installed in the dashboard a special lamp. It lights up if there is no charge.

How does the generator work?

Before you figure out why the battery charging light comes on, you need to understand the principle of the generator. On any car there are two power sources. It's a generator and battery. They are connected in parallel. Therefore, when the engine is running, the generator supplies voltage to the battery and charges it. And there is one feature. Regardless of the speed, the generator output voltage is always the same.

To stabilize it, a relay regulator is installed. Old cars used electromechanical type constructions. In modern, only semiconductor devices are used. The lamp, which is installed in the instrument panel, is included in the power supply circuit of the voltage regulator. It serves, in fact, a fuse. To understand the essence, it is necessary to thoroughly study the operation principle of the voltage regulator.

Voltage regulator

In the generators, two windings are rotor and stator winding. And the first performs the functions of the excitation winding. It is necessary to recall the theory: generation of electric power is impossible without a moving magnetic field. Therefore, it is sufficient to apply voltage to the rotor winding to obtain a magnetic field. Well, as the rotor is a moving part of the electric machine, it becomes clear that the magnetic field will rotate. And if the battery charging light periodically turns on, then this indicates that there is a small defect in the generator.

But why do they set the voltage regulator in the supply circuit of the field winding? After all, it is necessary to make stabilization in the stator chain. This is so, but it is worth remembering the theory: the magnitude of the magnetic field depends on the voltage at the output. Everything is very simple. It is sufficient to stabilize the supply in the rotor winding circuit so that there is no oscillation at the output. It is much easier to stabilize small currents than large ones (it can reach several tens of amperes).

Search for breakdowns

Suppose, after starting the engine, you notice that the battery charging light comes on. VAZ is subject to this problem, and it is relevant for any model. You need to check the following nodes:

1. The voltage regulator described above. On some cars, it can be installed under the hood, and not inside the generator.
2. Diode bridge. Possible failure of one or more semiconductors.
3. Belt of a drive of the generator. It can be badly stretched or there was a breakage, slippage. If the whistle is heard, it is possible to judge the breakdown of the bearing in the front cover.

The cause may also be broken wiring or poor-quality contact. Check first the wire coming from the "+" generator to the voltage regulator. Very often it is oxidized, covered with a layer of dust. Remove the brush holder and evaluate the wear of the brushes. If it is excessive, then a replacement must be made. Note that on most cars, the voltage regulator and the brush are integrated into one unit. Another reason is a breakdown in the ignition lock. But this malfunction is accompanied by the fact that several lamps in the dashboard light up.

Tools for repairs

In the event that the battery charging lamp on the revolutions lights up, it is most likely that the belt slips due to weak tension. But if this is all right, you need to arm yourself with the following tools:

• Multimeter (preferably a voltmeter with a wide scale).
• Control lamp for 12 volts and 2-3 watts of power.
• Flat and cross screwdrivers.
• Pliers, sandpaper, knife.

With these tools at hand, you can take up repairs if the battery charging light comes on, or there is another breakdown in the generator.

Breakdowns and their elimination

Let's say a voltmeter is installed in the car. And he shows that there is a charge. Also, the battery charging lamp lights up periodically or does not light at all. Voltage measurement directly on the battery terminals shows exactly 12 volts. But the capacity is lost, the starter does not rotate, and the tape recorder hardly works. First of all, clean all the thick wires that charge the battery. Measure the voltage at the "30" terminal of the generator. If it is larger than what is on the battery, wipe the terminal or change the wire.

If, on the instrument panel, the voltmeter shows the presence of charging, but the lamp does not light, and the battery is discharged, despite the normal voltage in the on-board network, perform a couple of simple actions. Turn on the maximum number of consumers and see how the voltmeter behaves. If the voltage drops sharply, stretch the alternator belt. It starts to slip, since under the load the EMF of the rotor counteracts the stator. And it is necessary to make a considerable effort. In addition, one of the pulleys may simply be worn. Then even the installation of a new belt will not save.

Internal breakdowns

The above situation can occur when a semiconductor diode breaks down. In the presence of a break in the stator winding, there is also a voltage drop under load. Disassemble the generator and conduct diagnostics of semiconductors. They have one-sided conductivity. Ring the stator windings to reveal a short to the housing. It is worth noting that a break with a multimeter can be found, but a bad contact is unlikely. For this purpose it is better to use a megger.

It is worth to inspect and brush the generator. If the battery light on the low battery lights up while the light is on, this also indicates that there are breakages described above. From brushes, too much depends. If they have a length of 5 mm or less, you can safely throw them away. And if the light bulb for charging the battery due to the failure of the brushes, the fault can be found very simply.

A few more common breakdowns

But most often it happens that the battery charging lamp does not light up, but there is a breakdown. And in case of burnout of the lamp itself, the voltage on the field winding is lost. It is easy to detect a malfunction - you need to check the filament of the lighting device itself. But most often the lamp blinks, it can briefly light up. Often the cause of this behavior is the broken contact in the supply circuit of the field winding. For elimination, clean all connectors using a knife, sandpaper, or apply a penetrating grease type WD-40.