Hi, this is a bit of a weird case... Basically I bought a couple of iPhones (6s 64GB) back in October 2015 in the Coventry Garden Apple Store in London to resell them in Spain. Turns out that Apple was really quick in rolling out the new iPhone in Spain and I had very little time to resell them. I got some really terrible offers, mixed with some personal problems and since I didn't need the money urgently, I STILL have these iPhones sealed in their boxes. Now I want to sell them but I am afraid that the battery might have depleted and my question is: How long do iPhone batteries hold their charge if they've never been turned on? Should I open them and charge them? That would remove the plastic and maybe lower the value? I'm looking at a loss one way or the other, I just want to know how you would proceed. Thank you and sorry for this weird question.