How Long Will the Car Battery Last If the Lights Are Left On?
2 Answers
If the parking lights have low power consumption, the battery can last overnight; if the front two headlights are xenon, they can stay on for about 8 hours. For more advanced vehicles with LED headlights, they can remain illuminated for approximately 14 hours. Additional Information: 1. Turn Signal Left On: Most car models on the market will activate the parking light function if the turn signal is left on. If the left turn signal is left on, the left parking light will stay lit, and the same applies to the right side. These parking lights consume much less power than headlights, and even if forgotten, only one side will be illuminated, not both, so the battery can generally last through the night without issue. 2. Turn Signal Power Consumption: The power consumption of turn signals varies by model, ranging from 10 watts to 21 watts. Taking 21 watts as an example, the total for all four turn signals (front and rear) would be 84 watts. Some models also have turn signals on the side mirrors and body, bringing the total power consumption close to that of two xenon headlights. In such cases, the battery might last around 9 hours.
That time when I drove back to my hometown, I was so tired that I forgot to turn off the lights, and the next morning the car wouldn't start. The mechanic checked and said the battery was completely drained—I had probably left them on for about seven and a half hours. Generally, newer car batteries are stronger and can last 5 to 8 hours, while older ones might die in less than 5 hours. It mainly depends on the battery capacity and the power consumption of the headlights. My car has standard headlights, with a power of around 100 watts. If it were smaller lights, like the interior reading lights, which consume less power, it might last over 10 hours without much issue. Since then, I've made it a habit to glance at the dashboard before getting out of the car, or to buy a car with automatic light shutoff—it saves a lot of hassle. Additionally, a drained battery not only prevents the car from starting but can also damage the battery itself, leading to premature failure. It's a good idea to have a garage check the battery's health regularly—a small expense can prevent bigger troubles. Keeping an emergency jump starter in your backpack is also helpful in case of issues. In short, don’t take it lightly—small things can turn into big problems.
