"GeorgeB" wrote in message

Now, let's have the alternator charging the battery, and have it at
15.5V or so ... now I have 3.8 volts across that current determining
resistor ... 12 times the "design". OUCH.

15.5V is not a normal charging voltage, and if sustained will ruin the
battery. It would only be a fault condition with a regulator gone
bad. I think you can safely calculate dropping resistors based on
14.5V max.

Fred F.