What do you associate with the words „light bulb“? Hopefully not just „burn out“. But we keep getting comments that contain precisely these words. So let’s take a close look at the reasons why automotive lamps fail. Today, we’ll focus on the problems caused by the operating voltage.
Most people think that the voltage in a car is 12 V. In reality, the on-board voltage when the engine is running is generally between 13.5 and 14 V, and in some cases even higher. Headlight lamps are therefore not designed for 12 V but for 13.2 V. The lifetime information relates to this voltage. The (standardized) 13.2 V is in keeping with practical experience. In cables, relays and switches a few tenths of a volt are always lost so that value in most cars is closer to 12 V. If not, there would be serious consequences for the life of the lamp. There is a rule of five here which states that a five percent deviation in the operating voltage will affect lamp life by 50 percent.
If the alternator supplies an extra five percent then the lamp will suffer and may last only half as long as it should. An extra five percent corresponds to a voltage of around 13.9 V. The voltage needs to be measured at the lamp terminals and not at the battery or at the alternator terminals. If you are confident about using a multimeter you can measure the voltage yourself.
As you can see, the operating voltage is a major cause of premature failure in light bulbs. So what can you do if your car is one of the ones running at high voltage? Well, first you need to check whether this high voltage is normal for the model. Some car manufacturers accept the disadvantages in order to ensure the battery recharges quickly. A qualified mechanic will be able to tell you what the operating voltage is on your car. If high voltage is detected, there are a number of possible causes. Such as a worn-out alternator. Even though the Voltage Regulator may be working properly, a low-quality or depleted battery can simulate an increased demand for current. Replacing such batteries will eliminate the problem of lamps burning out too soon.
We will be returning to this issue in the near future.