I charged my battery to roughly 90% prior to a 9 hole round of golf. I was using an app on the phone (Golfshot) to get distance information to the green. Around the 7th hole I got a low battery warning (20%), starting the 9th I got the 10% battery warning. Finished the round, packed up and had a beer. When I next checked the phone it was now up at 50%, it had not been charged since the round. Never seen that happen before.