With an ammeter in the circuit, the supply to your ignition switch is coming from the ammeter. The +ve side of the ammeter is wired to your battery, the -ve side to users. When current flows to the battery, the ammeter shows charge, when the current flows from the battery, the ammeter shows discharge.
I'm not sure why your ammeter is wired to your ignition switch. Normally, the ammeter is wired such that all current users or generators are downstream of the ammeter. Like when you turn your headlights on with the engine off, the ammeter should show discharge. Your charging system also has to be wired such that charging current goes through the ammeter. Hope this helps.
