Sorry Antonio.
I mistakenly omitted the word "not" from my previous answer, which I have now amended. You should not rely on a voltage reading to tell you about the battery health because the load imposed by a simple meter is only a few milliamps, which is not enough stress to show up internal faults. Professional testing should impose a load about 100,000 times a multimeter (i.e. about 200-300 amps which is what a starter motor draws,) in order to truly stress the battery.