Why does battery drain when my Galaxy S6 is powered off?

[AC Question]

Lately, I've noticed that my GS6 smartphone battery power drains--sometimes completely--after it has been powered off for hours. I tested it recently, charging it up to 100% and then powering off and storing it in a drawer for about 36 hours. When I turned it on, the battery indicator showed less than 50% power. I have upgraded the operating system, but I don't see why that would make any difference. This problem is pretty new--just in the last few weeks. But I'm very frustrated and unsure whether to stick with Samsung phones in the future. By the way, I'm on the Sprint network.

 

[Jerry Hildenbrand]

If you're 100% sure that it's powered off and draining the battery, take it into a Sprint store. It needs replaced.

That's a sign of a battery that's lost it's holding capacity.