YACT: Does the 12V socket draw power even when the device plugged in is "off"?

[NotoriousJTC]

Quick question.


If i leave an electronic device plugged into my car's 12V socket, and it's in the OFF position, does it still draw any power at all? Is any power still fed to it (for comparisions: a home appliance that is left plugged in to an outlet, but is not in use)?... I ask only because ive had bad experiences with car batteries and my poor ability to maintain them.


TIA.

 

[kt]

In short yes.

 

[jocycliff]

Actually it depends on the car. My Nissan truck has a lighter for the 12v power outlet and it is shut off when the truck is off. My girlfriend's Jeep Liberty is a 12v power outlet and is provided with constant power even when the vehicle is off.

 

[dmurray14]

I guess it really depends on what kind of "off" switch it is. If it is a true physical on or off switch that actually disconnects the power from the device right at or around the cigarette lighter, then yes, you're probably fine. If it is a digital push button on or off, then it is still drawing power even when its off (some circuits are left on, including the one that waits until you press the on button to power things up again)

Hope that helps..

Dan

 

[Oger]

Dan is correct, but even if it still draws power in the "off" mode, it is very little, not enough to kill your battery unless you are letting your vehicle sit for three months or more.
Lead acid batteries naturally discharge on their own even if left disconnected, when doing so it is wise to either charge the battery every few weeks or charge it with a floating battery charger.

 

[NotoriousJTC]

The car in question is my BMW 323i. The operation manual states that the cigarette lighter is always "on" even when the car is off.

The device in question is an aftermarket reading lamp i frequently use for work/school. I also use the 12V for other devices such as cell phone, but not in the same frequency. The lamp has an off "slider" on a seperate control box, a red light goes on and off to indicate the lamps power status. Now i realize the power consumed in this instance is very little, but because of other variables such as wiring i would prefer to know for sure if it is indeed in effect "on" even when "off".

Thank you for your replies thus far.

 

[dman]

Doubtful that a reading lamp is on when switched to off. Electronics with rechargeable batteries will sometimes draw a fair bit of power when 'off' as they are charging the batteries, but, I don't suspect that is the case here.

In fact, you probably should describe how frequently you have to change batteries and how often you are driving your car. For example, if you are changing batteries every 6mo-1yr and drive nearly everyday at least 15-20minutes then it's probably NOT the accessory devices. It may be the climate, the car, or actually a electrical system problem (Battery could be getting over/under charged while driving which eventually kills it).

If, however, you drive like once/week and change/manually charge batteries every other week... there's probably something draining the battery. I'd still suspect something else besides the 12v accessory plug, maybe a car alarm or a short somewhere, etc, or still the electrical system.

Of course if you do suspect it's the 12v accessory plug, just unplug it for a few weeks and see if it makes any difference.