Does Bluetooth drain power when it's not in use? Possible Duplicate:
  Will constantly having Bluetooth on drain my battery too fast?  




When Bluetooth is turned on, but not in use, is it still draining power? If so, how much relative to it being in use?
Yes. 
When it is on, but not in use, it continually scans for the device it has been previously paired with. 

This allows for it to do things like-- automagically connect to your car when you get in it.

However, the amount of battery drain is still minimal, even if it is continually scanning.