[petek]

If the ammeter is reading + numbers then the altenator is putting out more current than is being used by the electrical "stuff" and the excess is charging the battery.

If the ammeter is reading 0 then the altenator is putting out just the right amount of current for the electrical "stuff" and the battery is fully charged.

If the ammeter is reading -- then the electrical "stuff" (fan, fuel pump, spark box, radio, etc) is using more current than the altenator can provide while still keeping the battery charged.

Fundamentally.... don't worry 'bout it unless the ammeter is always reading negative numbers.