Yes, it shows a lower voltage..... which does not actually tell you that any current is flowing out of the battery. It only says the system's voltage is lower, and nothing about the battery's contribution and operation in that situation.
Not all ammeters are bad ju-ju; ammeters are fine if good and wired right. Piper and Cessna light aircraft came with them for several decades. No general issues with them, none at all; the ammeter is still in my '61 Cherokee and there were never any AD's on the ammeters. It has to stay there because there are no STC's to allow it to be removed. They were built better and the wiring was done right. And the early Mopar ammeters were indeed constructed differently. The later ones are surely suspect with their age; but none of the 5 new A/F bodies and 3 new C bodies that my family had when I was growing up ever had a hint of ammeter issues, both plastic and pre-plastic designs.
