Almot I have had badddd luck using digital for this because the sampling rate is 1-2 times per second. It sees peak to peak but it isn't a scope. The blur of changing numbers I cannot interpret. I haven't checked all AC digital meters but my meters cannot even make up their mind on a good alternator. When alternators are charging hard the waveform is obscured by voltage/+?/frequency. I am going to get a couple of meters to take with me when I tackle the Harbor Fright 500-amp carbon pile battery tester. Why fit it to the carbon pile? So the battery can be loaded down and maximum waveform amplitude can be established. Both meters, amperage and voltage will become digitalized. The AC meter of course, will be analog.
When doing this test, any large capacitors must be disconnected out of circuit. Power supplies, chargers, big amplifiers, etc. Capacitors dampen ripple so readings are made muddy. The .47 or 1.2 uf cap inside the alternator are not big enough to absorb bad ripple.
