Originally Posted By: dbrashear
The sensors I want are definitely nerdy: i still want a bluetooth prox sensor, because honestly, my or my wife's cellphone being there are the only triggers that really matter. Too bad leaving bluetooth enabled on the iPhone has an actual battery impact.


Seriously, it's so little power that it's in the noise. Leave it on, along with wifi. WiFi used to sleep at sub 1mA when associated to an access point, I believe Bluetooth was about 0.25mA.

If you assume that you have 100 hours standby with both wifi and bluetooth off, you'd have about 92 hours with both of them on. In the real world, where you do leave your house (hence wifi will be lower power) it's even less impact.

Really though, you should be using geofences to determine whether you're at home or not...