This has happened twice this week to me with my S6. I have a wireless charging stand (Verizon branded) that I'll set my phone on at night when I go to bed. And typically when I wake up in the morning the phone is fully charged. I'm usually in bed by 11, waking up at 6...so should be more than enough time to fully charge the phone, even if it were completely dead when putting it on the charger. This morning when I took the phone off the charger, it was only at 78%. When I put it on the charger last night it was around 40%. I thought the 78% charge was odd so I rebooted the phone. When it came back up, it was suddenly down to 65%! The other day this happened as well...Monday night I put the phone on the charger with about a 20% charge. When I got up, it was only at 65%. Any ideas why this may be? Could the wireless charger be on the fritz?