What is the reason for the headlights being on for 20 minutes but the car not starting?
2 Answers
The reasons why the headlights are on for 20 minutes but the car does not start are as follows: 1. Insufficient battery voltage: When the battery voltage is insufficient, the horn and lights can still work, but the car may not start. Specific detection method for low car battery voltage: Use a multimeter voltage range to test the battery voltage. If it is below 10V, consider replacing it; if it is around 11V, it can be used temporarily, but be prepared to replace it; if it is above 12V, it can be used normally. 2. Check the quality of the gasoline and carbon deposits: If the car has been driven for about 20,000 km, focus on checking the throttle, ignition switch, starter, fuel pump, sensors, and other components related to the starting and fuel supply system. 3. Starting too quickly: After powering on, do not start immediately. Wait for thirty seconds to one minute before ignition to see if it has any effect.
I've been driving for many years and have encountered the situation where the headlights are on but the car won't start several times, mainly due to a depleted battery. Leaving the headlights on for 20 minutes continuously discharges the battery. If the battery itself is old or severely drained, there won't be enough current to start the engine. Another factor is an issue with the charging system, such as a faulty alternator not charging the battery, which accelerates power loss when the headlights are on. Check if the battery terminals are loose or corroded, or use a multimeter to measure the battery voltage—if it's below 12 volts, it means the battery is dead. An emergency solution is to jump-start the car, but it's best to maintain the battery regularly, testing it every six months to avoid draining it unnecessarily in cold weather. This issue can be quite dangerous—if it happens at night, pull over safely, turn on the hazard lights, and handle the situation after ensuring safety.
