actually the fuse link must be rated to the nominal car load and not the alt. The fuse link will blown on a short and the ONLY device able to feed a short is the batt not the alt.

If your car would get an alt without a batt, the engine will stall when a short comes in.

Several misconceptions about this, starting with the WRONG name given to the ammeter as ALTERNATOR gauge, where really is a BATTERY gauge. An Alt will never discharge because is not an accumulator. An alt is able toi feed or not, but never get Charged or Discharged. The batt IS the device which gets Charge or Discharge.

If you start up the engine and disconect the alt, the ammeter will show discharge. But if you disconect the batt, the ammeter will show NOTHING, simply a death centered needle, while your alt is sourcing the car/engine. That t5ells you what really mesures the ammeter.