I've had my G3 gps on for 5-6 hours at a time when driving, I put the screen on the lowest brightness setting to save battery, I also have a power bank plugged into the USB to keep the battery full. Also I go out cycling and have 2 GPS tracking apps running, I can be out for 5 hours and I do this every weekend. I've had no issues with my G3. Also if you do start having problems with the G3 battery, at least you can swap it out for a replacement if your phone is out of Warranty.