I have no idea as to why FAM Sheet 12.00 shows the gauges upside down. But, I continue to ponder this in hopes of learning the how and why of ammeters.....maybe that's why I have a volt meter!
So, in simple terms, the ammeter indicates the direction of current flow (charge or discharge) and the relative amount of current flow. In the center of the ammeter gauge is zero current flow and all the way to the left and right on the gauge shows maximum charge or discharge.
The ammeter has a frame with a magnet attached to it and an armature with a needle attached to it. Without current flowing in the system, the needle is held at the center point of the gauge by the magnet. With current flowing in the system in either direction (charge or discharge) the magnetic field attracts the armature away from the magnet and the indicator needle gives a reading in relationship to the strength of the current.
It seems to me that the starter/battery connection should be the charge (+) side of the ammeter and the discharge side (-) or load should be on the other terminal of the ammeter gauge.
I'll close with this. If the system is charging, the current is flowing back to the battery. If the system is discharging, the current use (load/demand) is exceeding the current supply.
I hope you get this solved soon. Otherwise you'll need an eloquent way to say "If it shows a discharge, swap the wires to the other terminal."
