⚠️🔋 Battery charging lamp is on

Battery charging lamp - designed to control the operation of the battery charging system from the generator. It is located in a prominent place on the dashboard in the form of a schematic representation of the battery. The lamp lights up when the ignition is switched on and should go out immediately after the engine has been successfully started. This is its normal mode of operation. If the control lamp does not go out, flashes or glows at full intensity, this indicates a malfunction of the vehicle's battery charging system.

Connection diagram and principle of operation of the battery charging lamp

The figure below shows a typical diagram of a car battery charging system. The control lamp 4 is connected to the "+" of the battery 1 through the ignition switch 3. When the ignition is on, "-" to power the control lamp comes from the battery through the "mass" 8, diodes 7 and 9. After starting the engine, the generator starts to generate electric current. A "+" appears on pin 11 of the voltage regulator relay. As a result, the control lamp receives "+" and "+", which is why it does not glow. The driver sees that the generator and other elements of the system are working, and the battery is charging.

7 modes of operation of the control lamp

Despite the fact that the battery charging lamp is just an ordinary light bulb, it is a very informative diagnostic tool. She has several modes of operation, including regular and emergency. Knowledge of these modes will allow you to better understand the principle of operation of the system, and facilitate troubleshooting.

Mode 1. The lamp is on when the ignition is on

Normal mode of operation, indicating that the control lamp is working, and there are no problems in its power circuit. There is a battery, it is connected to the on-board network, and it is charged. The ignition switch is correct. You can start the engine.

Mode 2. The lamp does not light when the ignition is on

Emergency operation, indicating a malfunction in the battery charging system. The first step in such cases is to check the battery - whether it is charged and whether it is connected to the car's on-board network. If the "battery is on board", the next step is to check the lamp itself - it may have burned out. If this does not help, then it is worth looking for a problem in the wires responsible for powering the lamp in this mode of operation. The cause of the malfunction can also be the failure of the diodes in the generator.

Mode 3. The lamp goes out after starting the engine

Normal mode of operation, indicating that the generator is working and the battery is receiving a charge. All consumers are powered by a generator. On some vehicles, the lamp does not go out immediately after starting the engine, but after a few seconds. This is considered normal operation. If the lamp does not go out at idle, but does so at higher speeds, this indicates a malfunction in the battery charging system.

Mode 4. The lamp does not go out when the engine is running

Emergency operation, indicating a malfunction in the battery charging system. The battery is not being charged by the alternator. All consumers are powered by the battery, which is why it is discharged. Possible malfunctions indicated by the control lamp in this mode of operation are discussed below.

Mode 5. Lamp flashes

Emergency operation, indicating interruptions in the battery charging system from the generator. Most often occurs due to slippage of the alternator drive belt. It also happens due to poor contact in the power supply circuit of the control lamp.

Mode 6. The lamp shines in full heat

Emergency operation, indicating a partial malfunction of the generator. The reason is most often the failure of one of the three phases, which occurs due to a break in the power diodes or the stator winding. In such cases, the lamp starts to work normally at high engine speeds. At low throttle or idle, the problem returns.

Mode 7. The lamp flashes after the engine stops

Normal operating mode, indicating the stop of the generator and the termination of battery charging. On some vehicles, the lamp does not light up at this moment, which is also normal operation of the system.

10 reasons why the battery charge light is on when the engine is running

In most cases, the operation of the battery charge warning lamp indicates a malfunction of the generator. There is a separate detailed material about this on the Auto without a service station website. Sometimes the emergency operation of the lamp indicates problems with the battery. But more often, nevertheless, the reason lies in the generator.

Reason 1. Malfunction in the lamp power circuit

To identify or eliminate this malfunction, it is necessary to check the voltage at the battery terminals with the engine running. If the voltage is at the level of 13.8-14.8 V, this means that the charging system is functioning properly. The control lamp in such cases may burn due to problems in its power circuits. The reason may be a short circuit or failure of the auxiliary diode bridge. Troubleshooting is reduced to the continuity of these circuits.

Reason 2. The alternator belt is slipping or broken

If the drive belt breaks, the generator does not work, and the control lamp burns at full heat when the engine is running. You can determine this malfunction by visual inspection of the engine compartment. Please note that on some vehicles, a broken alternator belt promises more serious problems than a dead battery.

A slipping drive belt causes the warning light to flash or stay on intermittently while the engine is running. The problem manifests itself due to the weak tension of the belt or its natural wear. Sometimes slips occur in wet weather, when water from a puddle gets under the belt onto the alternator pulley. The burning of the control lamp in such cases is usually accompanied by a characteristic squeak. The problem goes away by itself after a while. You may need to pay attention to the condition or tension of the drive belt.

Reason 3. Jammed generator

The generator rotor rotates on two ball bearings, which have a very limited resource. When the bearings wear out, the generator may periodically stop or jam altogether. The control lamp flashes or stays on, depending on this. To check the bearings in the field, the alternator pulley must be released from the drive belt and rotated by hand. If the rotor does not rotate, or noticeably wedges at the same time, the bearings must be replaced.

Reason 4. Faulty voltage regulator

If the voltage regulator relay fails, the generator does not work and the second "+" is not supplied to the battery charging control lamp. Accordingly, it lights up when the engine is running, indicating a malfunction. To check the voltage regulator relay, it is necessary to measure the voltage at the battery terminals with the engine running. Readings below 13.8 V indicate a malfunction of this element.

Reason 5. Faulty generator brushes

Current-carrying brushes on many cars are made in one unit with a voltage regulator relay. Typical malfunctions: wear, damage or hanging in clips. To check the brush assembly, it must be removed from the generator and carefully inspected for damage, wear or sticking in the guides. Defective brushes must be replaced with new ones.

Reason 6. Malfunction of current-carrying rings of the generator

The brushes are constantly in contact with copper rings, which are fixed and rotate on the axis of the generator rotor. In case of wear or clogging with plaque, the electrical circuit breaks, the excitation of the generator windings stops, the system stops working. The battery charge control lamp, depending on the nature of the breakdown, can either blink or glow constantly. Most generators are equipped with removable current-carrying rings, which allows them to be replaced.

Reason 7. Open or breakdown of the diode bridge

In a classic car alternator, there are two diode bridges. One power, through which the current generated by the windings is rectified. When one or more power diodes fail, the battery charge control lamp glows at full dimmer. As the revs increase, it may begin to glow in full heat. The second diode bridge is auxiliary. It serves to excite the generator winding and is part of the power supply circuit for the battery charge control lamp. To determine the faulty diodes, you need a continuity with a multimeter. Broken or broken diodes are replaced with serviceable ones.

Reason 8. Breakage or short circuit of the generator windings

When one of the generator windings breaks or shorts, the control lamp glows at full heat. If two or more windings fail, the lamp burns with full heat, indicating a complete failure of the generator. To identify a malfunction, it is necessary to completely disassemble the assembly and test the windings with a multimeter. In the event of an open circuit or an inter turn circuit, the stator or the entire alternator of the car must be replaced.

Reason 9. The battery is defective

In some cases, the control lamp may burn while the engine is running with a fully functional charging system. If the generator and the voltage regulator relay are working, the problem is probably in the battery or the power wires with which it is connected to the on-board network. Inspect the battery terminals for oxides and corrosion. What is this problem, and how to deal with it, is described in detail in the material about the oxidation of battery terminals. If the conclusions are in order, you need to check the integrity of the terminals and power wires.

Reason 10. Bad contact in the battery charging system from the generator

Poor contact in the battery charging circuits from the generator can also cause the warning lamp to glow or blink. The search is carried out by means of visual inspection and step-by-step dialing of the following nodes:

• conclusions and power wiring of the battery;
• voltage regulator and brushes;
• power diode bridge;
• auxiliary diode bridge;
• control lamp and its installation location;
• ignition lock.

Please note that poor contact often occurs intermittently or under certain conditions (for example, when the weather is wet outside). In such cases, it is necessary to carry out preventive maintenance of all connections in the battery charging system from the generator.

The battery charging lamp lights up while driving - what to do?

In the event of a failure of the charging system and the power supply of the on-board network from the generator, a reserve capacity is provided in the battery. It is in any serviceable and normally charged battery. Often indicated on the case as a time in minutes (for example, 100 minutes). This means that this battery is capable of delivering 25 A for 100 minutes.

The vehicle's on-board network is also designed to operate in emergency mode in the event of a generator failure. The ignition system and other systems are powered in this mode from the battery. Therefore, if the battery charging lamp lights up on the way, you can continue driving using the reserve capacity of the battery.

Naturally, in order to be able to get to the house, garage or service in emergency mode, the battery must be serviceable and normally charged. As a rule, in such cases, "on the battery" you can safely drive up to 6 hours during the day, and at least 2 hours at night.

Operation of the car on the reserve capacity of the battery in some cases is prohibited. This applies to breakdowns associated with the jamming of the generator, when it is impossible to remove the drive belt from its pulley (for example, because of this, the cooling system pump will not work). In cars where the generator and gas distribution mechanism are driven from one belt, operation in the event of a breakdown of the assembly is also prohibited.

Conclusion

If the battery charging indicator lamp is on while the engine is running, it must be stopped and a preliminary diagnosis performed. In some cases, after inspection, the movement can be continued using the reserve capacity of the battery. If the failure of the generator or its drive can lead to the inoperability of other systems, further operation of the vehicle is prohibited.