Why isn't the car's alternator generating electricity?

First, with the engine running, check whether the alternator pulley is driving the alternator. If it is running normally, disconnect the positive terminal of the battery. If the car stalls immediately, this indicates that the alternator may not be generating electricity; If the engine does not stall, measure the voltage between the alternator’s positive output terminal and ground. Accelerate to vary the engine speed and observe whether the voltage fluctuates. If the voltage fluctuates and remains around 12V, the alternator is functioning normally; otherwise, there is a problem with the alternator. Once you have determined that the alternator is functioning properly, measure the output voltage of the voltage regulator while the engine is running (Note: You must also disconnect the positive terminal of the battery). If there is voltage present, this indicates that the alternator and regulator are outputting voltage normally. Otherwise, inspect the charging circuit, checking the fuses, plugs, sockets, and connectors.