What is the maximum allowable AC current from the alternator to the battery?

The maximum allowable AC current from the alternator to the battery is typically expressed as a percentage of the alternator's rated output, which is why the correct response involves 10% of that rating. This is particularly important because while the alternator's primary function is to provide a steady DC voltage to charge the battery and power the vehicle's electrical systems, some level of AC ripple is inherent in the output.

Exceeding 10% can indicate potential issues in the alternator’s rectifier or voltage regulation, which could lead to poor battery performance or damage over time. Thus, maintaining the AC current at or below this threshold is vital for ensuring the longevity and functionality of both the battery and the alternator. This percentage serves as a guideline for acceptable performance, helping technicians diagnose and address problems effectively in automotive electrical systems.

The other options provide numerical values that are not generally standardized or applicable across different vehicle models, making them less relevant in this context. The correct response is more universally applicable and aligns with industry practices.