OK so an interesting thing happened. I have an Odyssey battery with an Odyssey charger/tender. I usually hook it up if I am not going to drive it for a few days... longer times in the winter.
Anyhow, I charged it up and was around 13v when I took it off. After about 10 minutes off the tender it dropped to 12.5v... no big deal right? I decided to run it and test the alternator and it started charging the battery at 14.4v. So the alternator works!
However, it looks like the battery loses a ton of juice in a short amount of time. I checked for a parasitic draw and found nothing. Could I just have a bad battery? It's only 1.5 years old. Would the alternator not try to charge if its at 11v?
After charging the battery will settle down to 12.5
12.5 is pretty close to float. Memory says 2.09 per cell x 6 = 12.54 on a new battery.
You could take the battery to an auto parts store and have them put a load test on it to make sure.
My thought is if the battery was bad enough not to charge on the alternator then it shouldn't have worked on the one-ten battery charger.
Try to remember what you did just before the alternator kicked in.
If the battery has enough poop to crank the engine and is good enough to take charge from the wall unit then it should work with the alternator.
It is probably going to turn out to be something simple.
One night long long ago I was coming home and the alternator stopped charging while driving.
I was pulling my trailer so had those pre-led running lights plus the lights on the Toy.
I could tell the lights were getting dim but didn't realize just how much until I down shifted for a steep grade and the alt. kicked in and everything got bright outside.
Next day pulled the alternator apart to find a lose wire inside.