This is a stumper for me: To end with, I'm on my 4th alternator in 9 months. Ford OEM, Ford remanufactured, Chinese, and lastly new Bosch HD. There are 4 different things happening when the red charging icon lights up after starting: the icon comes on, system voltage stays at 12.2v until I stop the engine, let it cool off, and restart. or 2) the light comes on after starting, system voltage is 12.2v until the alternator goes up to 13.6v after 10 minutes or so, and the light stays on until restart. or 3) the light goes on after start, system voltage at 12.2v until the alternator starts charging at 13.6 v and the light goes out by itself. But lately, 4) the light comes on, even though I'm getting 13.6v 90 seconds after start.
It looks like the charge idiot light isn't connected to the alternator!