[nerys]

Well length of tethering is a bit of a misnomer. Since the data connection is only really active when your actively transmitting/recieving data. Its one of the most efficient ways of doing it. IE you use "no" sprint resources while your reading a page your loaded. Its all digital so it instantly (for the most part) connects and disconnects as needed. So Unless you have a continuous download going your not even using the radio 100% of that time probably less than 10% of that time. BT takes so little power your not going to overheat anything using it.