I have a Nokia Lumina 929 with the latest Denim software update. When I use any GPS navigation app - Waze, gMaps, Nokia Here - the battery drain is so excessive that the phone gets very warm at the rear near the bottom of the phone. In fact, on a recent trip to Colorado, when using the Nokia Here application - the battery drain was so excessive that even when plugged in to a 2.1A power supply the battery died after 250 miles of driving and the phone was almost too hot to touch at the rear bottom.