What is the procedure for checking charging system regulated voltage?

The procedure for checking the charging system regulated voltage involves measuring system voltage under specific conditions to ensure the alternator is functioning correctly. The correct choice highlights that measuring system voltage while the alternator output is below 1/3 provides a controlled environment where fluctuations in output can be effectively monitored.

Measuring the voltage when the alternator is not operating at its maximum capacity allows you to see how well the system operates under less demanding conditions. This is crucial for diagnosing potential issues with regulation and ensuring that the alternator can maintain proper voltage levels when the electrical load increases.

In contrast, using a carbon pile to control alternator output might not accurately reflect actual system conditions as it doesn't simulate the operational load of a vehicle. Measuring system voltage with the engine at 1000 rpm is part of the procedure, but it does not specify the alternator's output condition, which is essential for an accurate assessment. Turning on all electrical loads and running the engine at 1000 rpm could provide insights into system performance, but it may not effectively demonstrate regulated voltage under lower operational conditions. Understanding the context of each step in the procedure helps in diagnosing charging system performance accurately.