Things that drain phones the most: screen, GPS, and transferring massive amounts of data (especially over weak signal). Bluetooth connections and kilobytes of data are far down the list.
My 520 lasts about 10 hrs with navigation, plus a small USB battery pack can add plenty more run time in a pinch. Because I have one of the last flagship phones with a replaceable battery, my phone probably could last that long with GPS turned on if I used its massive replacement phone battery, but I wouldn't get anywhere close with the OEM battery than loses 15% an hour just idling.