As was mentioned before, the circuit breaker is meant to protect the wire. In this case it must be at least 60 amps because that is what could be flowing from the alternator to the battery.
I agree with your statement. But 60 amps would be really bad for the battery.
The maximum safe current to a battery can be approximated from the CCA or the Amp-hours but its going to be much less than that on a typical car battery we use. A quarter of the Ah rating.
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