When the engine is running, the main current source - the generator provides electric current to all consumers, including the ignition system, and charges the battery.
If the red battery discharge warning light is on in the instrument cluster, it means that no current is supplied from the alternator to the on-board network and the battery energy is being used up. The operation of a car with a burning battery discharge warning lamp is unacceptable, since sometimes the cause of the lamp to light up can be a short circuit in the wiring, leading to a fire in the engine compartment of the car. Stop the vehicle, turn off the engine, and determine what fault is causing the light to come on. If the cause of the malfunction was not a short circuit, and the battery was fully charged, you can drive to the garage without a generator, but it is better to try to fix the problem on the spot.
Checking electrical equipment
1. Check if the alternator drive belt is broken. If the belt breaks or the belt is worn to the point that the automatic tensioner does not maintain proper belt tension, replace the belt (see «Replacing accessory drive belts»).
2. If, even with normal belt tension, the signal lamp is still on, check the reliability of the wire connection to «positive» battery terminal...
3....to the starter...
4.... and the generator. Wires can be broken, broken inside the insulation, or with oxidized or unreliable contacts. Repair the problem and start the engine. If the charging current appears, you can continue driving.
If, after the measures taken, the discharge lamp continues to burn when the engine is running, then the possible cause of the malfunction lies in the generator itself. The reasons may be different, and it is better to eliminate them in a car service or garage, and you can only hope that there is enough energy in the battery to get to them.
USEFUL ADVICE: In order to reduce current consumption when driving a car with a faulty generator, if possible, turn off the audio system, unnecessary lighting, heater fan, heated windshield and rear windows, etc.