<![CDATA[The stability of alternator output voltage is important for maintaining modern diesel vehicle electrical systems, because additional loads such as headlights, cabin cooling, and audio systems can increase current demand and affect charging voltage. This study aims to analyze alternator output voltage under variations of electrical load on a vehicle with a 4V21 Euro 4 diesel engine. A field experiment was conducted on a vehicle with a 24-volt electrical system and the engine operating at idle speed. Data were collected using a scanner under three load conditions: no load at 0 W, medium load at 150 W, and full load with a reference power of 1,110 W. Each condition was tested five times, with a data collection duration of 20 minutes per test, conducted once per day for five days. The main parameter observed was alternator output voltage, while engine RPM and coolant temperature were recorded as supporting data. The results showed that the average alternator output voltage was 28.3 V under no-load conditions, 27.8 V under medium-load conditions, and 27.7 V under full-load conditions. The total voltage drop from no load to full load was 0.6 V. Engine RPM remained at an average of 651 rpm, and coolant temperature remained at 83.1°C. These results indicate that increasing electrical load reduces alternator output voltage; however, the decrease was relatively small, and the lowest voltage still met the operating range of the 24-volt charging system, indicating that the charging system operated properly under the tested load variations.]]>
