one wire Alternator and voltage regulator question

upload_2021-2-28_12-7-14.png

not the greatest or totally controlled experiment and I added some tests on the (+) side of the coil.
Yeah Mattax, the battery lost some ground after our crummy weather spell last week and did require some charging to get it to 12.5. It got up to 12.7 after running for 15 minutes or so this morning. I think that I am using the word ammeter and the gauge in the dash as the same thing erroneously. thanks for that...