This also had me going around in circles…
In a car, if it has an Ammeter, it indicates how much the battery is Charging … ie + = alternator is putting current INTO the battery, – ie Alternator OUTPUT
In the C172, the whole concept is different … The Ammeter is measuring how much current is being drawn FROM the battery.
So Its backwards, from a car …
Think of it as Battery Discharge amount – the more +ve it is, the more it is flattening your battery.
Use the Starter motor, and it maxes out POSITIVE.,
So, when the Plane is running, you do NOT want to see it go Positive, you want to see it stay negative.
Difficulty to remember, as one is so use to the Ammeter in a car.
Maybe Think of it as AMMETER WARNING … the more Positive it reads, the HIGHER the WARNING. ie it is measuring battery LOAD
- is BAD
- is GOOD
EDIT 1/6/2020
DISREGARD all above. The issue is the c172 Ammeter Gauge, most likely in a reversed animation.
> + is GOOD Charging
> - is BAD Discharging – eventaully leading to a flat battery, and being unable to start the Plane.