Cessna 172 Wiring Diagram - Wiring Diagrams Schematics - The route returned to the battery is a little more complex, but there wherein it says "battery feeder", you could see it is going via a 70a fuse, right down to where it connects to the battery contactor. So whilst the alternator transfer is on and the battery transfer is on (remaining the battery contactor), the alternator can price the battery. [In small cessnas this is a split master switch, but i'm not sure what it looks like in an archer.].
I think you misunderstand how the alternator, battery, and electric gadget are connected. An alternator places out dc voltage into the electric bus. It is used to offer electric electricity to plane systems, in addition to to recharge the battery from cranking and pre-begin light and radio utilization.
To reply your question especially about what the ammeter suggests, this will provide you with the amount of contemporary the alternator is supplying in amps. After startup you should see slightly more than usual because the battery recharges. You will in all likelihood see the range go up whilst you are transmitting at the radio. If you see this number get genuinely huge for no cause, there can be a fault inside the electrical gadget somewhere. If you see this quantity visit zero, it is feasible that the alternator has stopped running absolutely and your lighting and radios at the moment are jogging on battery for a confined quantity of time!.
You may see the alternator about 2/three of the manner up the diagram, simply to the left of center. The 'b' lead coming out of it is going immediately into the ammeter and to the dc strength bus (the huge bar alongside the pinnacle).