The idea is that the ammeter (a meter) is to read the lack of charge or no lack of charge .......so......... battery hot to one terminal of ammeter, everything else, including alternator, to other terminal. (All on the ammeter or a terminal block for added space.)
Alternator output's main duty is to charge the battery when battery voltage is low enough to allow current to flow. When battery is up, the flow is "blocked"/"equalized". Of course the output is regulated and the rate is per speed of alternator shaft.
Basically you want to see the needle always on the plus side or middle. A lot when alternator is charging battery and a little when battery is up.. If it shows discharge that's when you start checking. Alternators are good at charging at fairly low RPM's. However starter motor will have drawn down battery for a short time.
It would seem very silly to sell an ammeter without a shunt. The ammeter reads the shunt. An ammeter is a giant buss bar with a tiny bypass circuit called a shunt.
Didn't see Jerry's post, so Pete and Repeat.
