Siri and Location Alert Question

[bwphoto]

I'm guessing that to get the full benefit of Siri you'll need to leave your GPS on all the time. Does anyone do this currently? I feel like your battery would be toast in an hour. Or does Siri have some other magical way of knowing where you are that isn't a massive drain on the battery? Thanks-

 

[Kalaheo]

Perhaps it will suspend the gps until it gets info from the cell towers that you're getting close to your destination, then will activate the gps for greater accuracy.