Why does the temperature gauge rise when the headlights are turned on?
1 Answers
Turning on the headlights causes the temperature gauge to rise because the reference potentials for the instrument panel and the headlights are different. Here are the details: 1. Influencing factors: The headlights have a separate ground wire (grounding wire) and power supply wire from the generator, while the temperature gauge and other instruments are powered by the positive terminal of the battery. Due to poor contact at the negative terminal of the battery, the power supply to the instruments is in a low state. Because the generator regulator and the headlight ground wire are functioning properly, the output reference voltage of the generator's voltage regulator matches that of the headlight side. However, the battery ground wire (grounding wire) may have a voltage drop due to poor contact compared to the generator regulator's ground wire. When the headlights are turned on, the generator load increases, causing the output voltage to drop. The voltage regulator then increases the output to normal voltage. At this point, the headlight voltage is normal, and since the generator has already increased the output voltage, the battery terminal voltage also increases accordingly. This results in an increased power supply voltage to the temperature gauge, causing it to display a higher temperature. 2. Reason: The difference in reference potentials between the instrument panel and the headlights causes the regulator's reference potential to change when the headlights are turned on or off. As a result, the regulator's output voltage varies across the two unequal potential loads.
