Where does energy for devices plugged into the cigarette lighter port in car come from?

Question

Directly from the battery, or the alternator?

My guess and I could be wrong because I dont know much about cars, it depends on what position your car is in. If it's not on (to the point where the engine isn't on) then it runs directly off the battery. But if the engine was running, it runs off the alternator (and mabe the battery? If so by how much? Half? )

Here I pose another observation question though, most devices that are plugged into the port when the car is not on dont receive a charge anyway. So how is it that the battery is still able to drain? I know your lights can go, but that's beside the question...

Answer 1

When the car is running, the alternator provides more voltage than the battery to charge the battery and run lights and accessories.  Many non-USA cars turn off the lighter plug when the engine is off, but it would power from the battery with the key in accessory position.

One battery killer is leaving the interior light on overnight too many times, especially if it is normally automatic and you leave it in the manually on position.

Answer 2

I agree with the top part of your question , now for as your 12v port goes it pulls from the battery and if your car was running then the alternator would be recharging the battery while you used the 12v port.

Answer 3

If your battery has drained while your not in the car but have left a device plugged into your lighter socket, then the socket is probably hot (Live) all the time. Meanwhile the device you have may not charge properly when the batteries voltage drops as it dies.  End result two dead batteries.  But really your battery would have to be weak for this to happen.  There may be a short somewhere in your cars electrical or a bad voltage regulator/alternator etc.

Answer 4

  Its off the battery, the alternator charges the battery. On most new cars the cigar lighter is not powered when the car is off. On older cars the lighter was always hot. But back then people used them to smoke, now we call them "power outlets" and just use them to charge our cell phones and ipods that we arent useing when the car is off anyways. The only way they can cause a draw if the car is off is if there is a short. Unless of course your car does have "12v power outlets" or a "cigar lighter" that stays hot after the key is off.  

Answer 5

The power comes from the battery, the alternator charges the battery and supplies extra power to run the other things like lights/ radio/ ect, when the car is running.

Notice the lights dimm when you turn the car off? The power to most of the electrical divices runs through the ignition switch, so they don't drain the battery if you acidently left them on, including the power port (former cigarette lighter,) but some are not turned off like the headlights, radio breaklights and alarm system, some of the things you may want to run with the car off.

Answer 6

All powered 12v jacks in the car run directly from the battery.

the alternator basically keeps the battery at a constant current and keeps giving off electricity, But if the car is off the alternator is not running, Then it's not delivery any kind of  "charge" to the battery, Thus then the battery commits suicide.

Answer 7

battery