It all depends on if there is power coming through your car audio port. USB has the capability of carrying power and data but it may not have been set up that way. I would say that it would be but it would depend. If you have the Droid or any phone or kindle or anything else that charges via Micro USB plug it in and see if it is charging. It may not charge as fast as using a car charger but it would if nothing else keep you from loosing charge while you listen to music and all that stuff.