Looks like you're right Jim. Just did a quick test and got the following data.
Here's full-load (main beam, heater blower on full, rear fogs on and rear window heater on) at idle just after a cold start - idle admittedly is a bit slow as well.
Voltmeter on the dash says this:
Multimeter on the battery shows 12.28V - so pretty close.
Same load with the engine brought up to anywhere above idle and it jumps straight up to here:
Which reads as 13.93V according to my meter on the battery. Off-load it's a steady 14.2V, and sitting right on the black mark in the green zone on the voltmeter, which is obviously intended to signify "normal." It's a bit hard to come up with precise measurements on a non-calibrated instrument like this, but it seems at least functionally pretty accurate.
I was always taught when I was at the garage that it takes on average of 20-30 minutes of normal driving in most cars to recoup the charge used from the battery to start the engine, not sure how accurate this might be these days with the ridiculous outputs available from some alternators - especially with cars now commonly being equipped with AGM batteries which can accept charge much faster than conventional ones. Not sure where stop-start technology plays in there either...