Having now been able to replace my cigarette lighter on a 1999 Peugeot 206, it's become apparent that it's on an always live fuse rather than an ignition switched one.

Is this okay or will it drain the battery? Presumably leaving draining components like a sat nav is a bad plan, but how about the USB adapter on its own? Is it safe to just pull all the components out and leave the empty socket?

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    Unplug everything.
    – JoErNanO
    Oct 16, 2016 at 13:05
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    It is super, super useful to be able to charge things while you are not in the car. If nothing is plugged in, there is no energy being used. I leave a splitter with 3 different USB chargers always plugged in. I have 700 CCA battery and I only noticed it drain my battery once: when I got back from a two week vacation. Oct 16, 2016 at 14:31
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3 Answers 3


USB adapters typically do still have current draw.

I discovered this on my return from a two week holiday. I'd left my USB adapters plugged in and my battery was dead...

Admittedly I had 5 3A USB ports - they weren't supplying current to devices, but I guess the current draw from 5 unused ports is enough to drain the battery in that space of time.

So for short periods of time - not likely to be a problem, but if you can have a switched port, that would be safer for long periods away from the car.


Good question.

I worried about this too, because my Audi A4 (B7 2005 model) has an always on cigarette lighter.

My other car, a VW, is newer and has what I will call "traditional" functionality of it being on only when ignition is on.

I have a had a charger plugged in all the time, never drained the battery. (And yes the charger is on as it has a LED light on it).

Is it okay? Perhaps not if the user is not aware that this can lead to running the battery flat depending on what is plugged in..

Is this an advantage or a disadvantage? I guess thats a matter of personal opinion. In my case its been useful at times to charge the phone and not have to have the keys in the car. (Ie in public to leave phone in car charging).

Perhaps you need to get a charger is designed better and doesn't pull current when it isn't actually doing anything. I have a no name brand that is OK, also a Belkin too.


Totally okay. I fitted two ciggy ports to my 73 Series landrover. One runs a rearview camera and the other is for a USB adapter.

The circuit is always-on to the battery, but there's a manual switch as well, so I can choose to run it, or not. Since the screen is pretty obvious, its hard to accidentally leave it running.

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