FYI
1. Engine off - battery standing voltage.
With the engine off and fully charged battery, hook up the meter directly to the battery terminals(not clamp, bolt, nut, etc...). Read the meter as volts DC.
2. Engine running - lo idle - no load charging voltage.
Engine running at idle, all lights, accessories and AC off. Read the meter after voltage stabilizes from starting engine.
3. Engine running - hi idle - no load charging voltage.
Engine running at 1500 RPM, all lights, accessories and AC off. Read the meter.
4. Engine running - full load charging voltage.
Engine running at 2000 RPM, lights on high beams, AC on MAX(blower on high). Read the meter.
The "no load charging voltage at idle" and the "full load charging voltage at 2000 rpm" should be about 0.5 volts higher than the "battery standing voltage" at a minimum.
The "no load charging voltage at 1500 rpm+" is typically max output of the regulator.
Temperature reduces the output of the alternator as well, so a cold alternator output will be higher than the output when the alternator is hot.