Anonymous asked in Cars & TransportationMaintenance & Repairs · 6 years ago

05 Cadillac STS with the 4.6 V8 charging voltage question?

Our caddy just crapped out a three year old battery (dead cell) the new battery has been fully charged but my voltage while running the car is 14.5. now in the old days correct charge voltage was 12.5 to 13.6 and no higher than 14.0 or you could damage the battery but these new cars are different is this thing supposed to run that high on voltage or is the regulator failing in the alternator??

Thanks in advance for any help.

3 Answers

  • 6 years ago
    Best Answer

    Charging voltage was NEVER 12.5. In fact, 12.5 volts is a sign of a slightly discharged battery. Minimum charging voltage has always been 13.5. Max is 14.75. Anything over 16 is considered dangerous to vehicle electronics. That's why you should never use an old battery charger on a new vehicle.

  • 6 years ago

    Your alternator is charging the correct voltage! 12.5 - 13.6 volts will not charge the battery sufficiently.

    We have two GM cars. They both charge 14.2 volts after the car has been running 20 minutes. Right after start-up, the alternator will charge a half a volt higher. Any more than 14.4 volts continually will heat-up the battery and use up more battery acid.

  • 3 years ago


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