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[urgannagru]

I'm wondering how much car battery drain will happen if I keep a USB bluetooth adapter plugged in. Will I have a significant amount of battery life drained, or should I be fine assuming normal driving habits and an alternator? (daily (short distance) driver)

[GideonX]

How old is this battery? Specs on your BT adapter?

[snow veil]

why not run the (I'm assuming) 12v adapter -> bluetooth module through a 12v rail that's only enabled when the car is running? This way you won't have to worry about the device draining your battery when the car isn't in use (though I'd doubt the power requirements on the BT device would be much anyway)

[merlinicorpus]

I'm guessing you'll have trouble, particularly if you only drive short distances.  I don't know how much the adapter is pulling, but it doesn't take a whole lot to drain a car battery if it has a lot of hours to do it in.

[YucA]

As the smelly asian and others pointed out...

Size and age of the battery is quite important, as is the actual power draw of the adapter you are using...  All these will come into play.  

Granted, something that small shouldn't give you any problems.  Now, lets say you have a super small battery and you drive SUPER short distances not allowing the alt. time to bring the battery's juice back up then you will eventually drain it enough to give you issues.

I have an ipod adapter in my car that keeps the ipod charging 20mins after i shut the car off.  I havent felt the battery any lower.  This battery is less than a yr old though, and this isnt HOURS on end juicing the battery...

This is all considering you want the adapter to continue its charge cycle after you shut off...  If you really dont care about this, I would strongly consider hard wiring the adapter to an Ignition source like the Snowy Veilia said.

[Skylined]

It won't hurt, they are around 70A, that's plenty for a small bluetooth adapter.
The biggest drain that a car's battery gets, is when you start the engine, once the engine gets going, you get electrcity from the alternator.

[urgannagru]

Its a car thats less than 1.5 years old (08 altima). I'm not sure about the battery specs or the BT adapter specs.

There are 2 lighter adapters in the car, one of which does power down when the car powers down. The problem is, when I start up the car if I use that outlet, the BT adapter resets, and then my phone doesn't automatically reconnect, so I was hoping to just leave it on so it can reconnect without hassles.

[urgannagru]

I have been running the car with the bluetooth setup as described, and it worked fine for months now until last week, when the battery was finally drained. I would probably have been fine if I drove in a way that charged the battery more. Oh well, lesson learned.