Nokia Lumia 820 - How can I prevent HERE Drive from using too much battery?

To keep your phone battery from draining too quickly, it's best to connect the phone to an in-car charger when you're using HERE Drive.

When you're not using HERE Drive, remember to close the app completely by pressing the back key to the left of the Windows key.To see which apps are running in the background, long press the back button.You can also turn on the battery saver:  Settings > Battery saver. This will automatically switch off your GPS if HERE Drive is left running in the background when you're not using it.