How to measure the car battery with a multimeter

The multimeter can be used to measure your car battery and know its state of charge.
You must perform several measurements of the voltage of the car or motorcycle battery to know its status:
Measure empty, that is, measure the battery without any type of consumption
Measure the battery with consumption
Measure the battery when it is being charged
The measurement of the empty battery should give enyre 12V and 13V when the battery is charged.
If we have a measurement between 0V and 11.8V then there is a strong indication that the battery is fully or partially discharged.
Then we must apply consumption to the battery, turn on the lights for example, and measure the voltage.
The battery voltage should drop a few tenths of a volt, less than 1 volt, if this happens it is because the battery is in good charging condition.
When starting the engine, the battery receives a charge from the alternator or generator, and its voltage must rise until it reaches the float voltage, which is between 13V and 14V.