Why does the car battery drain when you leave the headlights on?

I'm no techie about autos, I'm just curious. What's the difference if the car is on/off? If you could drive the whole night with headlights on, how come it doesn't drain the battery?Why does the car battery drain when you leave the headlights on?
Yes it does.

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The reason is that your car has a charger (alternator) that recharges or powers all electrical system if the engine is running. If the engine is not running then your battery is supplying all the electrical power.



If you don't believe me, just ask anybody who ever left their lights on.

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Ignore all the people below who's making fun of your question. Everybody's knowledge starts somewhere. There was time when even they didn't know what they know now.



There are no bad students as long as the student is interested in learning. There are plenty of bad teachers who thinks they are too smart for their students.
the reason you can drive all night with the lights on is because as the car is on the alternator is charging the battery. no alternator charging the battery, no lights on all night. same with any other light in your car. watch that pesky truck light and glove box light. those will drain the battery too. it draws poer from it. just like a AA bettery in your remote. eventually it will use all the charge that bettery has. hope that helps! good luck!Why does the car battery drain when you leave the headlights on?
win the motor is runing the car makes power for the lights to run off av but win the motor is off the car can't make power for the lights so the battery goes died be caz the battery holds power
The electrical system in a car is powered by the alternator when the car is running. It also keeps the battery fully charged. The battery is designed to hold a specific charge in order to start the car and can power the electrical system (lights, radio, etc) for a relatively short period. If the headlights (major power consumer) are left on while the car is off and it is an older model which doesn't compensate by turning the lights off automatically then eventually, just like a flashlight, the battery will run dead.Why does the car battery drain when you leave the headlights on?
haha wow dont have to be a genius for this one man
Why does my bed get cold ? Its got a blanket!
When your car is running the alternator which is generally belt driven is charging the battery in order to keep a constant flow of electricity to the vehicle. When your is not running the alternator cannot recharge the battery hence draining the battery of all energy.
.... So he can understand........lol something with less big words.



When your car is ON its using gas to run things. and those things keep your battery juiced up. But if your car is OFF then its not using any gas so there is nothing to keep your battery juiced up so it dies.
When the car is turned on there is a generator which comes to life. The head light is then powered by the generator. There is no battery power loss.

With the car turned off, only power source is battery, which keeps depleting when headlights are on.