Depending upon ambient temperature, charging voltage generally varies between 14.8 and 13.5 volts. The actual charging voltage designed into a voltage regulator is dependent upon factors such as how far the alternator is located from the battery and the ambient air temperature surrounding the battery as calculated by the PCM.
If you switch off the engine, the battery voltage must be 12.6 volts or above. This is known as the “resting voltage” phenomenon. If you don’t have a multimeter, you may test the battery voltage by starting the engine and turning on the headlights. Is 11.9 Volt Sufficient Able To Start A Car?
The charging voltage should be between 13.9v to 14.4v. Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other. If the voltage at the battery and alternator don't match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring.
Now comparing the voltage on the battery (on the terminals not on the connector), we can see that it has dropped from 14.66 to 14.11 volts. This is a slightly higher drop of 0.55 volts compared to the 0.50 spec and could be improved with a larger charge cable between the alternator and the battery.
An automotive alternator generates from 13.8 volts to 14.3 volts at idle without turning the alternator lights or equipment on. A completely charged battery should have a voltage from alternator reading of more than 12.6 volts. Moreover, the actual output voltage will normally be 1-½ to 2 volts greater than the battery voltage.
Measure the voltage across the battery and the big bat alternator terminal to alternator case. There are two things that you are looking for. The charging voltage should be between 13.9v to 14.4v. Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other.