Chosen Solution
I recently changed the battery on my iPhone 5s because the old one would die quickly so I put a new one in and I’m still having the same issue. Last night I left it fully charged and when I woke up 6 hours later the phone was completely dead.
If you use an aftermarket charger, sounds like the U2 IC on your iPhones main board is fried. Google IPhone 5s U2 IC to see more.
