James;

I didn't know at first where you were going with the child's ear analogy, so I was intrigued and read it to the end...
"Even if I do not know what I am seeing each spring - I will see if anything changes."...OK, so your point is to know the normal baseline, and then you'll be able to recognize any abnormality...I understand and agree...the Bosch Gen/VReg based Chg Sys is highly reliable as it is based on sensing currents and magnetism, unfortunately neither of these can be seen unaided...so to help with having something more than just a visual baseline, I would suggest connecting a Digital Voltmeter to the terminals of the VReg while performing your tests (measuring Currents with clamp-on current probes is left for the experts!), to associate VReg action with voltages, as ALL operation will be affected by the (Battery) buss voltage (which determines currents through the sensing coils of the VReg)...don't forget, the Gen/Vreg combination is controlled by currents and their resulting magnetic action in the VReg.

Explanation of what all this technical mumbo-jumbo means here: https://www.sw-em.com/Bosch%20Generator%20based%20Ch%20Sys%20in%20Detail.htm

Cheers