What setting should a digital multimeter (DMM) be on to check the charging voltage of a battery?

To check the charging voltage of a battery, the digital multimeter (DMM) should be set to the DC volts mode. This is because automotive batteries produce direct current (DC) voltage, and measuring the voltage in this mode allows for an accurate reading of the battery's charging voltage.

When checking for correct charging voltage, typically while the engine is running, the DMM will provide a voltage reading that indicates whether the alternator is functioning properly and supplying the correct voltage to charge the battery. A healthy charging system generally produces a voltage between 13.7 to 14.7 volts under normal operating conditions.

Using the other settings would not yield correct or meaningful results. For example, setting it to AC volts would measure alternating current, which is not what is present in a car's electrical system. Similarly, DC amps is used for measuring current rather than voltage, and AC amps would also measure alternating current, which is irrelevant in this case. Therefore, identifying the right DMM setting is crucial for accurately diagnosing the charging system and ensuring the battery is receiving the proper voltage.