not healthy if at any point of the car is driven (proton), the volt drops below 13.5v. Minimum is 13.5v when aircond (at full blast), headlamp (high beam), foglights, room lamp, window heater, wipers & radio turned on (even for a 15yrs old Proton). Most proton circuit voltage when every electrical switch is turned on will display 13.5-13.6v. Only occasionally for cars with big ICE, or 100/120w spotlights using 75/90A alternator & 70A battery shows 13.3-13.5. On 100A alternator + 70A batt it should still show 13.6v. but on initial startup of the day, it should make 14.1-14.4v with 60A & 70A battery, regardless of dry or wet cell, and what amp of alternator.
Many possibilites that may have led your car doing 13.3v and its not something that can be advised easily through writings, but it is something that can be confirmed that your car's electrical system is not well and need to be sort out immediately. However, do use a multimeter first (tap to battery while engine's running) to get the voltage reading correctly. Some voltmeter may show shyte reading... like those fake Apexi pen timer or... fake brand voltmeter.