High voltage

In normal every day use, a high rated alternator would put out the same current as any other alternator.
There's two problems with high rated alternators( besides that some it is a marketting numbers game).
1. An alternator's rating is usually from its max output at higher rpms. Sometimes a higher max output is obtained at the expense of low rpm power output.
2. A high current demand situation is when a battery is run down. A discharged battery will initially suck a lot of current. If an alternator is capable of providing over 40 amps for recharging, that's way above what the wiring can handle. Its also not doing the battery any good.

Its really important to understand a few basic principles.
a. Power will come from which ever power source has the highest voltage.
b. Devices draw power.
- Alternator or battery only supplies as much power as demanded.
- Battery demand is a big variable. Generally its zero (fully charged). But when discharged it can draw a lot if allowed to.
Understanding Charging Systems with Ammeter