what voltage regulator? Battery charges to 12V, Alternator generates 14.4V...
If you test the voltage in the car when the car is running (ie when alternator is generating power), you will test ~14.4V. There is no voltage regulator that brings this down to 12V at a high level. (<- Hmm, that may be inaccurate) Perhaps individual devices bring it down, but they probably bring it down to 5V. Amps tend to use the full voltage (while adding capacitance to stabilize the voltage), as you'll see most are spec'd out at creating more power at 14.4V than at 12V. If they had a voltage regulator to bring it down to 12V everytime, this 14.4V power increase wouldn't be possible. So, at the battery, there is 14.4V when the alternator is supplying power.
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