Not much chance of drain the battery. The B.T switches off on the car and whilst the ignition is off the B.T. is not connected. If you are on long journey you can always use the usb port to charge your iPhone ....Any phone with B.T. on all the time will drain faster than off...newtojuke said:i feel so much better now that in the morning i won't have issues when starting, was getting very worried.