Car battery is not charging Skoda Octavia

There are two sources of current in a car - a battery and a generator. The battery is used when starting the engine and for supplying the starter and other consumers with an electric current of 12 V when the engine is not running.
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 Skoda Octavia battery warning light is on, it means that the current is not supplied from the generator to the on-board network and the energy reserve of the battery is consumed - the car battery is not charging. The operation of a car with a burning battery discharge warning lamp is unacceptable, since sometimes the cause of the lamp on fire 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 the electrical equipment - if the car battery is not charging

1. Check for a broken accessory drive belt. If a break occurs, replace the belt and adjust its tension.
2. If the belt is intact, check its tension.
USEFUL ADVICE
The manufacturer recommends checking the tension of the auxiliary drive belt using a special strain gauge tester. The tension in this case is measured in arbitrary units! If you don't have a tester, use the "rule of thumb" by applying pressure to the strap with your thumb and measuring the deflection with a ruler. According to this universal rule, if the distance between the centers of the pulleys is 180-280 mm, the deflection should be approximately 6 mm, and if the distance is 300-400 mm, then the deflection should be 13 mm.

3. If even after tensioning the belt, the signal lamp is still on, check the wires connected to the “positive” ...
NOTE
The protective cap of the terminal has been removed for clarity.

4 ... and the "mass" battery terminals ...

5. ... to the starter.

6 ...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 charging lamp continues to burn when the engine is running, then the possible cause of the malfunction lies in the generator itself. There may be several reasons 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
If the car battery is not charging, in order to reduce current consumption when driving a car with a faulty alternator, turn off the audio system, unnecessary lights, heater fan, rear window heating and other devices, if possible.

Source: http://skoda-octavia2.ru/index.php/neispravnosti-skoda-octavia/43-avtomobilnyi-akkumulator-ne-zaryazhaetsya.html