I have an ammeter in my car and a GM 12Si 94-amp alternator...

It can barelly maintain 11.8 vdc at idle (monitoring with Autoprom and a laptop). I can actually see that as the RPM goes up the battery voltage goes up to a steady 13.3 vdc.

I'm running fuel injection with a 730 ECM. Now, I suppose that there might be some heavier loading at speed, but my ammeter pegs at +40 when at full speed....doesn't look quite right.

Any ideas?

 

How old is the alternator?

 

Voltage drop from overloading the ammeter maybe? FWIW they are totally useless to see how much the whole car is drawing. They are only useful when testing to see if something is working properly/checking why fuses are blowing.