Not being too savvy with gadgets i seek help or advice.My last ride i nearly flattened the phone battery,100% down to 5% on a 27 mile ride.So i have a Lumia 640lte phone running on Windows 8.Anyone got any ideas what app will not drain the battery.i have looked at Striver and an add on for £2-49 so i can send to Strava.Advice welcome.