"An alternator/rectifier/voltage regulator, or battery charger, needs to
put out 14.4-14.8V to properly charge a car battery."

I like to see 15.5 when cold.

Another thing to note is that some cars actually pull more current when running than when cranking. Surprised the hell out of me to find that out. It was a fairly decent engine but three coils and six fuel injectors would not run on this partly dead battery when the charging system failed. But it would crank. Damndest thing.

Huh, in the old days the radio was the biggest drain, with a vibrator and tubes and such.